The patch below does not apply to the 6.1-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable(a)vger.kernel.org>.
To reproduce the conflict and resubmit, you may use the following commands:
git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.1.y
git checkout FETCH_HEAD
git cherry-pick -x bda745ee8fbb63330d8f2f2ea4157229a5df959e
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2025101311-walnut-drivable-cfbc@gregkh' --subject-prefix 'PATCH 6.1.y' HEAD^..
Possible dependencies:
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From bda745ee8fbb63330d8f2f2ea4157229a5df959e Mon Sep 17 00:00:00 2001
From: Steven Rostedt <rostedt(a)goodmis.org>
Date: Fri, 10 Oct 2025 23:51:42 -0400
Subject: [PATCH] tracing: Fix tracing_mark_raw_write() to use buf and not ubuf
The fix to use a per CPU buffer to read user space tested only the writes
to trace_marker. But it appears that the selftests are missing tests to
the trace_maker_raw file. The trace_maker_raw file is used by applications
that writes data structures and not strings into the file, and the tools
read the raw ring buffer to process the structures it writes.
The fix that reads the per CPU buffers passes the new per CPU buffer to
the trace_marker file writes, but the update to the trace_marker_raw write
read the data from user space into the per CPU buffer, but then still used
then passed the user space address to the function that records the data.
Pass in the per CPU buffer and not the user space address.
TODO: Add a test to better test trace_marker_raw.
Cc: stable(a)vger.kernel.org
Cc: Masami Hiramatsu <mhiramat(a)kernel.org>
Cc: Mark Rutland <mark.rutland(a)arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers(a)efficios.com>
Cc: Andrew Morton <akpm(a)linux-foundation.org>
Link: https://lore.kernel.org/20251011035243.386098147@kernel.org
Fixes: 64cf7d058a00 ("tracing: Have trace_marker use per-cpu data to read user space")
Reported-by: syzbot+9a2ede1643175f350105(a)syzkaller.appspotmail.com
Closes: https://lore.kernel.org/all/68e973f5.050a0220.1186a4.0010.GAE@google.com/
Signed-off-by: Steven Rostedt (Google) <rostedt(a)goodmis.org>
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 0fd582651293..bbb89206a891 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -7497,12 +7497,12 @@ tracing_mark_raw_write(struct file *filp, const char __user *ubuf,
if (tr == &global_trace) {
guard(rcu)();
list_for_each_entry_rcu(tr, &marker_copies, marker_list) {
- written = write_raw_marker_to_buffer(tr, ubuf, cnt);
+ written = write_raw_marker_to_buffer(tr, buf, cnt);
if (written < 0)
break;
}
} else {
- written = write_raw_marker_to_buffer(tr, ubuf, cnt);
+ written = write_raw_marker_to_buffer(tr, buf, cnt);
}
return written;
The patch below does not apply to the 6.6-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable(a)vger.kernel.org>.
To reproduce the conflict and resubmit, you may use the following commands:
git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.6.y
git checkout FETCH_HEAD
git cherry-pick -x bda745ee8fbb63330d8f2f2ea4157229a5df959e
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2025101310-shrapnel-prune-60b1@gregkh' --subject-prefix 'PATCH 6.6.y' HEAD^..
Possible dependencies:
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From bda745ee8fbb63330d8f2f2ea4157229a5df959e Mon Sep 17 00:00:00 2001
From: Steven Rostedt <rostedt(a)goodmis.org>
Date: Fri, 10 Oct 2025 23:51:42 -0400
Subject: [PATCH] tracing: Fix tracing_mark_raw_write() to use buf and not ubuf
The fix to use a per CPU buffer to read user space tested only the writes
to trace_marker. But it appears that the selftests are missing tests to
the trace_maker_raw file. The trace_maker_raw file is used by applications
that writes data structures and not strings into the file, and the tools
read the raw ring buffer to process the structures it writes.
The fix that reads the per CPU buffers passes the new per CPU buffer to
the trace_marker file writes, but the update to the trace_marker_raw write
read the data from user space into the per CPU buffer, but then still used
then passed the user space address to the function that records the data.
Pass in the per CPU buffer and not the user space address.
TODO: Add a test to better test trace_marker_raw.
Cc: stable(a)vger.kernel.org
Cc: Masami Hiramatsu <mhiramat(a)kernel.org>
Cc: Mark Rutland <mark.rutland(a)arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers(a)efficios.com>
Cc: Andrew Morton <akpm(a)linux-foundation.org>
Link: https://lore.kernel.org/20251011035243.386098147@kernel.org
Fixes: 64cf7d058a00 ("tracing: Have trace_marker use per-cpu data to read user space")
Reported-by: syzbot+9a2ede1643175f350105(a)syzkaller.appspotmail.com
Closes: https://lore.kernel.org/all/68e973f5.050a0220.1186a4.0010.GAE@google.com/
Signed-off-by: Steven Rostedt (Google) <rostedt(a)goodmis.org>
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 0fd582651293..bbb89206a891 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -7497,12 +7497,12 @@ tracing_mark_raw_write(struct file *filp, const char __user *ubuf,
if (tr == &global_trace) {
guard(rcu)();
list_for_each_entry_rcu(tr, &marker_copies, marker_list) {
- written = write_raw_marker_to_buffer(tr, ubuf, cnt);
+ written = write_raw_marker_to_buffer(tr, buf, cnt);
if (written < 0)
break;
}
} else {
- written = write_raw_marker_to_buffer(tr, ubuf, cnt);
+ written = write_raw_marker_to_buffer(tr, buf, cnt);
}
return written;
The patch below does not apply to the 6.12-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable(a)vger.kernel.org>.
To reproduce the conflict and resubmit, you may use the following commands:
git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.12.y
git checkout FETCH_HEAD
git cherry-pick -x bda745ee8fbb63330d8f2f2ea4157229a5df959e
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2025101308-chip-shredding-7707@gregkh' --subject-prefix 'PATCH 6.12.y' HEAD^..
Possible dependencies:
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From bda745ee8fbb63330d8f2f2ea4157229a5df959e Mon Sep 17 00:00:00 2001
From: Steven Rostedt <rostedt(a)goodmis.org>
Date: Fri, 10 Oct 2025 23:51:42 -0400
Subject: [PATCH] tracing: Fix tracing_mark_raw_write() to use buf and not ubuf
The fix to use a per CPU buffer to read user space tested only the writes
to trace_marker. But it appears that the selftests are missing tests to
the trace_maker_raw file. The trace_maker_raw file is used by applications
that writes data structures and not strings into the file, and the tools
read the raw ring buffer to process the structures it writes.
The fix that reads the per CPU buffers passes the new per CPU buffer to
the trace_marker file writes, but the update to the trace_marker_raw write
read the data from user space into the per CPU buffer, but then still used
then passed the user space address to the function that records the data.
Pass in the per CPU buffer and not the user space address.
TODO: Add a test to better test trace_marker_raw.
Cc: stable(a)vger.kernel.org
Cc: Masami Hiramatsu <mhiramat(a)kernel.org>
Cc: Mark Rutland <mark.rutland(a)arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers(a)efficios.com>
Cc: Andrew Morton <akpm(a)linux-foundation.org>
Link: https://lore.kernel.org/20251011035243.386098147@kernel.org
Fixes: 64cf7d058a00 ("tracing: Have trace_marker use per-cpu data to read user space")
Reported-by: syzbot+9a2ede1643175f350105(a)syzkaller.appspotmail.com
Closes: https://lore.kernel.org/all/68e973f5.050a0220.1186a4.0010.GAE@google.com/
Signed-off-by: Steven Rostedt (Google) <rostedt(a)goodmis.org>
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 0fd582651293..bbb89206a891 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -7497,12 +7497,12 @@ tracing_mark_raw_write(struct file *filp, const char __user *ubuf,
if (tr == &global_trace) {
guard(rcu)();
list_for_each_entry_rcu(tr, &marker_copies, marker_list) {
- written = write_raw_marker_to_buffer(tr, ubuf, cnt);
+ written = write_raw_marker_to_buffer(tr, buf, cnt);
if (written < 0)
break;
}
} else {
- written = write_raw_marker_to_buffer(tr, ubuf, cnt);
+ written = write_raw_marker_to_buffer(tr, buf, cnt);
}
return written;
Use check_add_overflow() to guard against a potential integer overflow
when adding the binary blob lengths in asymmetric_key_generate_id() and
return -EOVERFLOW accordingly. This prevents a possible buffer overflow
when copying data from potentially malicious X.509 fields that can be
arbitrarily large, such as ASN.1 INTEGER serial numbers, issuer names,
etc.
Also use struct_size() to calculate the number of bytes to allocate for
the new asymmetric key id.
Cc: stable(a)vger.kernel.org
Fixes: 7901c1a8effb ("KEYS: Implement binary asymmetric key ID handling")
Signed-off-by: Thorsten Blum <thorsten.blum(a)linux.dev>
---
Changes in v2:
- Use check_add_overflow() and error out as suggested by Lukas
- Update patch description
- Add Fixes: tag and @stable for backporting
- Link to v1: https://lore.kernel.org/lkml/20251007185220.234611-2-thorsten.blum@linux.de…
---
crypto/asymmetric_keys/asymmetric_type.c | 9 ++++++---
1 file changed, 6 insertions(+), 3 deletions(-)
diff --git a/crypto/asymmetric_keys/asymmetric_type.c b/crypto/asymmetric_keys/asymmetric_type.c
index ba2d9d1ea235..bd96f799757d 100644
--- a/crypto/asymmetric_keys/asymmetric_type.c
+++ b/crypto/asymmetric_keys/asymmetric_type.c
@@ -11,6 +11,7 @@
#include <crypto/public_key.h>
#include <linux/seq_file.h>
#include <linux/module.h>
+#include <linux/overflow.h>
#include <linux/slab.h>
#include <linux/ctype.h>
#include <keys/system_keyring.h>
@@ -141,12 +142,14 @@ struct asymmetric_key_id *asymmetric_key_generate_id(const void *val_1,
size_t len_2)
{
struct asymmetric_key_id *kid;
+ size_t len;
- kid = kmalloc(sizeof(struct asymmetric_key_id) + len_1 + len_2,
- GFP_KERNEL);
+ if (check_add_overflow(len_1, len_2, &len))
+ return ERR_PTR(-EOVERFLOW);
+ kid = kmalloc(struct_size(kid, data, len), GFP_KERNEL);
if (!kid)
return ERR_PTR(-ENOMEM);
- kid->len = len_1 + len_2;
+ kid->len = len;
memcpy(kid->data, val_1, len_1);
memcpy(kid->data + len_1, val_2, len_2);
return kid;
--
2.51.0
Hi,
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The patch below does not apply to the 5.10-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable(a)vger.kernel.org>.
To reproduce the conflict and resubmit, you may use the following commands:
git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.10.y
git checkout FETCH_HEAD
git cherry-pick -x 64cf7d058a005c5c31eb8a0b741f35dc12915d18
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2025101305-harsh-moisture-93ae@gregkh' --subject-prefix 'PATCH 5.10.y' HEAD^..
Possible dependencies:
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From 64cf7d058a005c5c31eb8a0b741f35dc12915d18 Mon Sep 17 00:00:00 2001
From: Steven Rostedt <rostedt(a)goodmis.org>
Date: Wed, 8 Oct 2025 12:45:10 -0400
Subject: [PATCH] tracing: Have trace_marker use per-cpu data to read user
space
It was reported that using __copy_from_user_inatomic() can actually
schedule. Which is bad when preemption is disabled. Even though there's
logic to check in_atomic() is set, but this is a nop when the kernel is
configured with PREEMPT_NONE. This is due to page faulting and the code
could schedule with preemption disabled.
Link: https://lore.kernel.org/all/20250819105152.2766363-1-luogengkun@huaweicloud…
The solution was to change the __copy_from_user_inatomic() to
copy_from_user_nofault(). But then it was reported that this caused a
regression in Android. There's several applications writing into
trace_marker() in Android, but now instead of showing the expected data,
it is showing:
tracing_mark_write: <faulted>
After reverting the conversion to copy_from_user_nofault(), Android was
able to get the data again.
Writes to the trace_marker is a way to efficiently and quickly enter data
into the Linux tracing buffer. It takes no locks and was designed to be as
non-intrusive as possible. This means it cannot allocate memory, and must
use pre-allocated data.
A method that is actively being worked on to have faultable system call
tracepoints read user space data is to allocate per CPU buffers, and use
them in the callback. The method uses a technique similar to seqcount.
That is something like this:
preempt_disable();
cpu = smp_processor_id();
buffer = this_cpu_ptr(&pre_allocated_cpu_buffers, cpu);
do {
cnt = nr_context_switches_cpu(cpu);
migrate_disable();
preempt_enable();
ret = copy_from_user(buffer, ptr, size);
preempt_disable();
migrate_enable();
} while (!ret && cnt != nr_context_switches_cpu(cpu));
if (!ret)
ring_buffer_write(buffer);
preempt_enable();
It's a little more involved than that, but the above is the basic logic.
The idea is to acquire the current CPU buffer, disable migration, and then
enable preemption. At this moment, it can safely use copy_from_user().
After reading the data from user space, it disables preemption again. It
then checks to see if there was any new scheduling on this CPU. If there
was, it must assume that the buffer was corrupted by another task. If
there wasn't, then the buffer is still valid as only tasks in preemptable
context can write to this buffer and only those that are running on the
CPU.
By using this method, where trace_marker open allocates the per CPU
buffers, trace_marker writes can access user space and even fault it in,
without having to allocate or take any locks of its own.
Cc: stable(a)vger.kernel.org
Cc: Masami Hiramatsu <mhiramat(a)kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers(a)efficios.com>
Cc: Luo Gengkun <luogengkun(a)huaweicloud.com>
Cc: Wattson CI <wattson-external(a)google.com>
Cc: Linus Torvalds <torvalds(a)linux-foundation.org>
Link: https://lore.kernel.org/20251008124510.6dba541a@gandalf.local.home
Fixes: 3d62ab32df065 ("tracing: Fix tracing_marker may trigger page fault during preempt_disable")
Reported-by: Runping Lai <runpinglai(a)google.com>
Tested-by: Runping Lai <runpinglai(a)google.com>
Closes: https://lore.kernel.org/linux-trace-kernel/20251007003417.3470979-2-runping…
Signed-off-by: Steven Rostedt (Google) <rostedt(a)goodmis.org>
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index b3c94fbaf002..0fd582651293 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -4791,12 +4791,6 @@ int tracing_single_release_file_tr(struct inode *inode, struct file *filp)
return single_release(inode, filp);
}
-static int tracing_mark_open(struct inode *inode, struct file *filp)
-{
- stream_open(inode, filp);
- return tracing_open_generic_tr(inode, filp);
-}
-
static int tracing_release(struct inode *inode, struct file *file)
{
struct trace_array *tr = inode->i_private;
@@ -7163,7 +7157,7 @@ tracing_free_buffer_release(struct inode *inode, struct file *filp)
#define TRACE_MARKER_MAX_SIZE 4096
-static ssize_t write_marker_to_buffer(struct trace_array *tr, const char __user *ubuf,
+static ssize_t write_marker_to_buffer(struct trace_array *tr, const char *buf,
size_t cnt, unsigned long ip)
{
struct ring_buffer_event *event;
@@ -7173,20 +7167,11 @@ static ssize_t write_marker_to_buffer(struct trace_array *tr, const char __user
int meta_size;
ssize_t written;
size_t size;
- int len;
-
-/* Used in tracing_mark_raw_write() as well */
-#define FAULTED_STR "<faulted>"
-#define FAULTED_SIZE (sizeof(FAULTED_STR) - 1) /* '\0' is already accounted for */
meta_size = sizeof(*entry) + 2; /* add '\0' and possible '\n' */
again:
size = cnt + meta_size;
- /* If less than "<faulted>", then make sure we can still add that */
- if (cnt < FAULTED_SIZE)
- size += FAULTED_SIZE - cnt;
-
buffer = tr->array_buffer.buffer;
event = __trace_buffer_lock_reserve(buffer, TRACE_PRINT, size,
tracing_gen_ctx());
@@ -7196,9 +7181,6 @@ static ssize_t write_marker_to_buffer(struct trace_array *tr, const char __user
* make it smaller and try again.
*/
if (size > ring_buffer_max_event_size(buffer)) {
- /* cnt < FAULTED size should never be bigger than max */
- if (WARN_ON_ONCE(cnt < FAULTED_SIZE))
- return -EBADF;
cnt = ring_buffer_max_event_size(buffer) - meta_size;
/* The above should only happen once */
if (WARN_ON_ONCE(cnt + meta_size == size))
@@ -7212,14 +7194,8 @@ static ssize_t write_marker_to_buffer(struct trace_array *tr, const char __user
entry = ring_buffer_event_data(event);
entry->ip = ip;
-
- len = copy_from_user_nofault(&entry->buf, ubuf, cnt);
- if (len) {
- memcpy(&entry->buf, FAULTED_STR, FAULTED_SIZE);
- cnt = FAULTED_SIZE;
- written = -EFAULT;
- } else
- written = cnt;
+ memcpy(&entry->buf, buf, cnt);
+ written = cnt;
if (tr->trace_marker_file && !list_empty(&tr->trace_marker_file->triggers)) {
/* do not add \n before testing triggers, but add \0 */
@@ -7243,6 +7219,169 @@ static ssize_t write_marker_to_buffer(struct trace_array *tr, const char __user
return written;
}
+struct trace_user_buf {
+ char *buf;
+};
+
+struct trace_user_buf_info {
+ struct trace_user_buf __percpu *tbuf;
+ int ref;
+};
+
+
+static DEFINE_MUTEX(trace_user_buffer_mutex);
+static struct trace_user_buf_info *trace_user_buffer;
+
+static void trace_user_fault_buffer_free(struct trace_user_buf_info *tinfo)
+{
+ char *buf;
+ int cpu;
+
+ for_each_possible_cpu(cpu) {
+ buf = per_cpu_ptr(tinfo->tbuf, cpu)->buf;
+ kfree(buf);
+ }
+ free_percpu(tinfo->tbuf);
+ kfree(tinfo);
+}
+
+static int trace_user_fault_buffer_enable(void)
+{
+ struct trace_user_buf_info *tinfo;
+ char *buf;
+ int cpu;
+
+ guard(mutex)(&trace_user_buffer_mutex);
+
+ if (trace_user_buffer) {
+ trace_user_buffer->ref++;
+ return 0;
+ }
+
+ tinfo = kmalloc(sizeof(*tinfo), GFP_KERNEL);
+ if (!tinfo)
+ return -ENOMEM;
+
+ tinfo->tbuf = alloc_percpu(struct trace_user_buf);
+ if (!tinfo->tbuf) {
+ kfree(tinfo);
+ return -ENOMEM;
+ }
+
+ tinfo->ref = 1;
+
+ /* Clear each buffer in case of error */
+ for_each_possible_cpu(cpu) {
+ per_cpu_ptr(tinfo->tbuf, cpu)->buf = NULL;
+ }
+
+ for_each_possible_cpu(cpu) {
+ buf = kmalloc_node(TRACE_MARKER_MAX_SIZE, GFP_KERNEL,
+ cpu_to_node(cpu));
+ if (!buf) {
+ trace_user_fault_buffer_free(tinfo);
+ return -ENOMEM;
+ }
+ per_cpu_ptr(tinfo->tbuf, cpu)->buf = buf;
+ }
+
+ trace_user_buffer = tinfo;
+
+ return 0;
+}
+
+static void trace_user_fault_buffer_disable(void)
+{
+ struct trace_user_buf_info *tinfo;
+
+ guard(mutex)(&trace_user_buffer_mutex);
+
+ tinfo = trace_user_buffer;
+
+ if (WARN_ON_ONCE(!tinfo))
+ return;
+
+ if (--tinfo->ref)
+ return;
+
+ trace_user_fault_buffer_free(tinfo);
+ trace_user_buffer = NULL;
+}
+
+/* Must be called with preemption disabled */
+static char *trace_user_fault_read(struct trace_user_buf_info *tinfo,
+ const char __user *ptr, size_t size,
+ size_t *read_size)
+{
+ int cpu = smp_processor_id();
+ char *buffer = per_cpu_ptr(tinfo->tbuf, cpu)->buf;
+ unsigned int cnt;
+ int trys = 0;
+ int ret;
+
+ if (size > TRACE_MARKER_MAX_SIZE)
+ size = TRACE_MARKER_MAX_SIZE;
+ *read_size = 0;
+
+ /*
+ * This acts similar to a seqcount. The per CPU context switches are
+ * recorded, migration is disabled and preemption is enabled. The
+ * read of the user space memory is copied into the per CPU buffer.
+ * Preemption is disabled again, and if the per CPU context switches count
+ * is still the same, it means the buffer has not been corrupted.
+ * If the count is different, it is assumed the buffer is corrupted
+ * and reading must be tried again.
+ */
+
+ do {
+ /*
+ * If for some reason, copy_from_user() always causes a context
+ * switch, this would then cause an infinite loop.
+ * If this task is preempted by another user space task, it
+ * will cause this task to try again. But just in case something
+ * changes where the copying from user space causes another task
+ * to run, prevent this from going into an infinite loop.
+ * 100 tries should be plenty.
+ */
+ if (WARN_ONCE(trys++ > 100, "Error: Too many tries to read user space"))
+ return NULL;
+
+ /* Read the current CPU context switch counter */
+ cnt = nr_context_switches_cpu(cpu);
+
+ /*
+ * Preemption is going to be enabled, but this task must
+ * remain on this CPU.
+ */
+ migrate_disable();
+
+ /*
+ * Now preemption is being enabed and another task can come in
+ * and use the same buffer and corrupt our data.
+ */
+ preempt_enable_notrace();
+
+ ret = __copy_from_user(buffer, ptr, size);
+
+ preempt_disable_notrace();
+ migrate_enable();
+
+ /* if it faulted, no need to test if the buffer was corrupted */
+ if (ret)
+ return NULL;
+
+ /*
+ * Preemption is disabled again, now check the per CPU context
+ * switch counter. If it doesn't match, then another user space
+ * process may have schedule in and corrupted our buffer. In that
+ * case the copying must be retried.
+ */
+ } while (nr_context_switches_cpu(cpu) != cnt);
+
+ *read_size = size;
+ return buffer;
+}
+
static ssize_t
tracing_mark_write(struct file *filp, const char __user *ubuf,
size_t cnt, loff_t *fpos)
@@ -7250,6 +7389,8 @@ tracing_mark_write(struct file *filp, const char __user *ubuf,
struct trace_array *tr = filp->private_data;
ssize_t written = -ENODEV;
unsigned long ip;
+ size_t size;
+ char *buf;
if (tracing_disabled)
return -EINVAL;
@@ -7263,6 +7404,16 @@ tracing_mark_write(struct file *filp, const char __user *ubuf,
if (cnt > TRACE_MARKER_MAX_SIZE)
cnt = TRACE_MARKER_MAX_SIZE;
+ /* Must have preemption disabled while having access to the buffer */
+ guard(preempt_notrace)();
+
+ buf = trace_user_fault_read(trace_user_buffer, ubuf, cnt, &size);
+ if (!buf)
+ return -EFAULT;
+
+ if (cnt > size)
+ cnt = size;
+
/* The selftests expect this function to be the IP address */
ip = _THIS_IP_;
@@ -7270,32 +7421,27 @@ tracing_mark_write(struct file *filp, const char __user *ubuf,
if (tr == &global_trace) {
guard(rcu)();
list_for_each_entry_rcu(tr, &marker_copies, marker_list) {
- written = write_marker_to_buffer(tr, ubuf, cnt, ip);
+ written = write_marker_to_buffer(tr, buf, cnt, ip);
if (written < 0)
break;
}
} else {
- written = write_marker_to_buffer(tr, ubuf, cnt, ip);
+ written = write_marker_to_buffer(tr, buf, cnt, ip);
}
return written;
}
static ssize_t write_raw_marker_to_buffer(struct trace_array *tr,
- const char __user *ubuf, size_t cnt)
+ const char *buf, size_t cnt)
{
struct ring_buffer_event *event;
struct trace_buffer *buffer;
struct raw_data_entry *entry;
ssize_t written;
- int size;
- int len;
-
-#define FAULT_SIZE_ID (FAULTED_SIZE + sizeof(int))
+ size_t size;
size = sizeof(*entry) + cnt;
- if (cnt < FAULT_SIZE_ID)
- size += FAULT_SIZE_ID - cnt;
buffer = tr->array_buffer.buffer;
@@ -7309,14 +7455,8 @@ static ssize_t write_raw_marker_to_buffer(struct trace_array *tr,
return -EBADF;
entry = ring_buffer_event_data(event);
-
- len = copy_from_user_nofault(&entry->id, ubuf, cnt);
- if (len) {
- entry->id = -1;
- memcpy(&entry->buf, FAULTED_STR, FAULTED_SIZE);
- written = -EFAULT;
- } else
- written = cnt;
+ memcpy(&entry->id, buf, cnt);
+ written = cnt;
__buffer_unlock_commit(buffer, event);
@@ -7329,8 +7469,8 @@ tracing_mark_raw_write(struct file *filp, const char __user *ubuf,
{
struct trace_array *tr = filp->private_data;
ssize_t written = -ENODEV;
-
-#define FAULT_SIZE_ID (FAULTED_SIZE + sizeof(int))
+ size_t size;
+ char *buf;
if (tracing_disabled)
return -EINVAL;
@@ -7342,6 +7482,17 @@ tracing_mark_raw_write(struct file *filp, const char __user *ubuf,
if (cnt < sizeof(unsigned int))
return -EINVAL;
+ /* Must have preemption disabled while having access to the buffer */
+ guard(preempt_notrace)();
+
+ buf = trace_user_fault_read(trace_user_buffer, ubuf, cnt, &size);
+ if (!buf)
+ return -EFAULT;
+
+ /* raw write is all or nothing */
+ if (cnt > size)
+ return -EINVAL;
+
/* The global trace_marker_raw can go to multiple instances */
if (tr == &global_trace) {
guard(rcu)();
@@ -7357,6 +7508,27 @@ tracing_mark_raw_write(struct file *filp, const char __user *ubuf,
return written;
}
+static int tracing_mark_open(struct inode *inode, struct file *filp)
+{
+ int ret;
+
+ ret = trace_user_fault_buffer_enable();
+ if (ret < 0)
+ return ret;
+
+ stream_open(inode, filp);
+ ret = tracing_open_generic_tr(inode, filp);
+ if (ret < 0)
+ trace_user_fault_buffer_disable();
+ return ret;
+}
+
+static int tracing_mark_release(struct inode *inode, struct file *file)
+{
+ trace_user_fault_buffer_disable();
+ return tracing_release_generic_tr(inode, file);
+}
+
static int tracing_clock_show(struct seq_file *m, void *v)
{
struct trace_array *tr = m->private;
@@ -7764,13 +7936,13 @@ static const struct file_operations tracing_free_buffer_fops = {
static const struct file_operations tracing_mark_fops = {
.open = tracing_mark_open,
.write = tracing_mark_write,
- .release = tracing_release_generic_tr,
+ .release = tracing_mark_release,
};
static const struct file_operations tracing_mark_raw_fops = {
.open = tracing_mark_open,
.write = tracing_mark_raw_write,
- .release = tracing_release_generic_tr,
+ .release = tracing_mark_release,
};
static const struct file_operations trace_clock_fops = {
The patch below does not apply to the 5.15-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable(a)vger.kernel.org>.
To reproduce the conflict and resubmit, you may use the following commands:
git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.15.y
git checkout FETCH_HEAD
git cherry-pick -x 64cf7d058a005c5c31eb8a0b741f35dc12915d18
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2025101303-unsterile-observant-971f@gregkh' --subject-prefix 'PATCH 5.15.y' HEAD^..
Possible dependencies:
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From 64cf7d058a005c5c31eb8a0b741f35dc12915d18 Mon Sep 17 00:00:00 2001
From: Steven Rostedt <rostedt(a)goodmis.org>
Date: Wed, 8 Oct 2025 12:45:10 -0400
Subject: [PATCH] tracing: Have trace_marker use per-cpu data to read user
space
It was reported that using __copy_from_user_inatomic() can actually
schedule. Which is bad when preemption is disabled. Even though there's
logic to check in_atomic() is set, but this is a nop when the kernel is
configured with PREEMPT_NONE. This is due to page faulting and the code
could schedule with preemption disabled.
Link: https://lore.kernel.org/all/20250819105152.2766363-1-luogengkun@huaweicloud…
The solution was to change the __copy_from_user_inatomic() to
copy_from_user_nofault(). But then it was reported that this caused a
regression in Android. There's several applications writing into
trace_marker() in Android, but now instead of showing the expected data,
it is showing:
tracing_mark_write: <faulted>
After reverting the conversion to copy_from_user_nofault(), Android was
able to get the data again.
Writes to the trace_marker is a way to efficiently and quickly enter data
into the Linux tracing buffer. It takes no locks and was designed to be as
non-intrusive as possible. This means it cannot allocate memory, and must
use pre-allocated data.
A method that is actively being worked on to have faultable system call
tracepoints read user space data is to allocate per CPU buffers, and use
them in the callback. The method uses a technique similar to seqcount.
That is something like this:
preempt_disable();
cpu = smp_processor_id();
buffer = this_cpu_ptr(&pre_allocated_cpu_buffers, cpu);
do {
cnt = nr_context_switches_cpu(cpu);
migrate_disable();
preempt_enable();
ret = copy_from_user(buffer, ptr, size);
preempt_disable();
migrate_enable();
} while (!ret && cnt != nr_context_switches_cpu(cpu));
if (!ret)
ring_buffer_write(buffer);
preempt_enable();
It's a little more involved than that, but the above is the basic logic.
The idea is to acquire the current CPU buffer, disable migration, and then
enable preemption. At this moment, it can safely use copy_from_user().
After reading the data from user space, it disables preemption again. It
then checks to see if there was any new scheduling on this CPU. If there
was, it must assume that the buffer was corrupted by another task. If
there wasn't, then the buffer is still valid as only tasks in preemptable
context can write to this buffer and only those that are running on the
CPU.
By using this method, where trace_marker open allocates the per CPU
buffers, trace_marker writes can access user space and even fault it in,
without having to allocate or take any locks of its own.
Cc: stable(a)vger.kernel.org
Cc: Masami Hiramatsu <mhiramat(a)kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers(a)efficios.com>
Cc: Luo Gengkun <luogengkun(a)huaweicloud.com>
Cc: Wattson CI <wattson-external(a)google.com>
Cc: Linus Torvalds <torvalds(a)linux-foundation.org>
Link: https://lore.kernel.org/20251008124510.6dba541a@gandalf.local.home
Fixes: 3d62ab32df065 ("tracing: Fix tracing_marker may trigger page fault during preempt_disable")
Reported-by: Runping Lai <runpinglai(a)google.com>
Tested-by: Runping Lai <runpinglai(a)google.com>
Closes: https://lore.kernel.org/linux-trace-kernel/20251007003417.3470979-2-runping…
Signed-off-by: Steven Rostedt (Google) <rostedt(a)goodmis.org>
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index b3c94fbaf002..0fd582651293 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -4791,12 +4791,6 @@ int tracing_single_release_file_tr(struct inode *inode, struct file *filp)
return single_release(inode, filp);
}
-static int tracing_mark_open(struct inode *inode, struct file *filp)
-{
- stream_open(inode, filp);
- return tracing_open_generic_tr(inode, filp);
-}
-
static int tracing_release(struct inode *inode, struct file *file)
{
struct trace_array *tr = inode->i_private;
@@ -7163,7 +7157,7 @@ tracing_free_buffer_release(struct inode *inode, struct file *filp)
#define TRACE_MARKER_MAX_SIZE 4096
-static ssize_t write_marker_to_buffer(struct trace_array *tr, const char __user *ubuf,
+static ssize_t write_marker_to_buffer(struct trace_array *tr, const char *buf,
size_t cnt, unsigned long ip)
{
struct ring_buffer_event *event;
@@ -7173,20 +7167,11 @@ static ssize_t write_marker_to_buffer(struct trace_array *tr, const char __user
int meta_size;
ssize_t written;
size_t size;
- int len;
-
-/* Used in tracing_mark_raw_write() as well */
-#define FAULTED_STR "<faulted>"
-#define FAULTED_SIZE (sizeof(FAULTED_STR) - 1) /* '\0' is already accounted for */
meta_size = sizeof(*entry) + 2; /* add '\0' and possible '\n' */
again:
size = cnt + meta_size;
- /* If less than "<faulted>", then make sure we can still add that */
- if (cnt < FAULTED_SIZE)
- size += FAULTED_SIZE - cnt;
-
buffer = tr->array_buffer.buffer;
event = __trace_buffer_lock_reserve(buffer, TRACE_PRINT, size,
tracing_gen_ctx());
@@ -7196,9 +7181,6 @@ static ssize_t write_marker_to_buffer(struct trace_array *tr, const char __user
* make it smaller and try again.
*/
if (size > ring_buffer_max_event_size(buffer)) {
- /* cnt < FAULTED size should never be bigger than max */
- if (WARN_ON_ONCE(cnt < FAULTED_SIZE))
- return -EBADF;
cnt = ring_buffer_max_event_size(buffer) - meta_size;
/* The above should only happen once */
if (WARN_ON_ONCE(cnt + meta_size == size))
@@ -7212,14 +7194,8 @@ static ssize_t write_marker_to_buffer(struct trace_array *tr, const char __user
entry = ring_buffer_event_data(event);
entry->ip = ip;
-
- len = copy_from_user_nofault(&entry->buf, ubuf, cnt);
- if (len) {
- memcpy(&entry->buf, FAULTED_STR, FAULTED_SIZE);
- cnt = FAULTED_SIZE;
- written = -EFAULT;
- } else
- written = cnt;
+ memcpy(&entry->buf, buf, cnt);
+ written = cnt;
if (tr->trace_marker_file && !list_empty(&tr->trace_marker_file->triggers)) {
/* do not add \n before testing triggers, but add \0 */
@@ -7243,6 +7219,169 @@ static ssize_t write_marker_to_buffer(struct trace_array *tr, const char __user
return written;
}
+struct trace_user_buf {
+ char *buf;
+};
+
+struct trace_user_buf_info {
+ struct trace_user_buf __percpu *tbuf;
+ int ref;
+};
+
+
+static DEFINE_MUTEX(trace_user_buffer_mutex);
+static struct trace_user_buf_info *trace_user_buffer;
+
+static void trace_user_fault_buffer_free(struct trace_user_buf_info *tinfo)
+{
+ char *buf;
+ int cpu;
+
+ for_each_possible_cpu(cpu) {
+ buf = per_cpu_ptr(tinfo->tbuf, cpu)->buf;
+ kfree(buf);
+ }
+ free_percpu(tinfo->tbuf);
+ kfree(tinfo);
+}
+
+static int trace_user_fault_buffer_enable(void)
+{
+ struct trace_user_buf_info *tinfo;
+ char *buf;
+ int cpu;
+
+ guard(mutex)(&trace_user_buffer_mutex);
+
+ if (trace_user_buffer) {
+ trace_user_buffer->ref++;
+ return 0;
+ }
+
+ tinfo = kmalloc(sizeof(*tinfo), GFP_KERNEL);
+ if (!tinfo)
+ return -ENOMEM;
+
+ tinfo->tbuf = alloc_percpu(struct trace_user_buf);
+ if (!tinfo->tbuf) {
+ kfree(tinfo);
+ return -ENOMEM;
+ }
+
+ tinfo->ref = 1;
+
+ /* Clear each buffer in case of error */
+ for_each_possible_cpu(cpu) {
+ per_cpu_ptr(tinfo->tbuf, cpu)->buf = NULL;
+ }
+
+ for_each_possible_cpu(cpu) {
+ buf = kmalloc_node(TRACE_MARKER_MAX_SIZE, GFP_KERNEL,
+ cpu_to_node(cpu));
+ if (!buf) {
+ trace_user_fault_buffer_free(tinfo);
+ return -ENOMEM;
+ }
+ per_cpu_ptr(tinfo->tbuf, cpu)->buf = buf;
+ }
+
+ trace_user_buffer = tinfo;
+
+ return 0;
+}
+
+static void trace_user_fault_buffer_disable(void)
+{
+ struct trace_user_buf_info *tinfo;
+
+ guard(mutex)(&trace_user_buffer_mutex);
+
+ tinfo = trace_user_buffer;
+
+ if (WARN_ON_ONCE(!tinfo))
+ return;
+
+ if (--tinfo->ref)
+ return;
+
+ trace_user_fault_buffer_free(tinfo);
+ trace_user_buffer = NULL;
+}
+
+/* Must be called with preemption disabled */
+static char *trace_user_fault_read(struct trace_user_buf_info *tinfo,
+ const char __user *ptr, size_t size,
+ size_t *read_size)
+{
+ int cpu = smp_processor_id();
+ char *buffer = per_cpu_ptr(tinfo->tbuf, cpu)->buf;
+ unsigned int cnt;
+ int trys = 0;
+ int ret;
+
+ if (size > TRACE_MARKER_MAX_SIZE)
+ size = TRACE_MARKER_MAX_SIZE;
+ *read_size = 0;
+
+ /*
+ * This acts similar to a seqcount. The per CPU context switches are
+ * recorded, migration is disabled and preemption is enabled. The
+ * read of the user space memory is copied into the per CPU buffer.
+ * Preemption is disabled again, and if the per CPU context switches count
+ * is still the same, it means the buffer has not been corrupted.
+ * If the count is different, it is assumed the buffer is corrupted
+ * and reading must be tried again.
+ */
+
+ do {
+ /*
+ * If for some reason, copy_from_user() always causes a context
+ * switch, this would then cause an infinite loop.
+ * If this task is preempted by another user space task, it
+ * will cause this task to try again. But just in case something
+ * changes where the copying from user space causes another task
+ * to run, prevent this from going into an infinite loop.
+ * 100 tries should be plenty.
+ */
+ if (WARN_ONCE(trys++ > 100, "Error: Too many tries to read user space"))
+ return NULL;
+
+ /* Read the current CPU context switch counter */
+ cnt = nr_context_switches_cpu(cpu);
+
+ /*
+ * Preemption is going to be enabled, but this task must
+ * remain on this CPU.
+ */
+ migrate_disable();
+
+ /*
+ * Now preemption is being enabed and another task can come in
+ * and use the same buffer and corrupt our data.
+ */
+ preempt_enable_notrace();
+
+ ret = __copy_from_user(buffer, ptr, size);
+
+ preempt_disable_notrace();
+ migrate_enable();
+
+ /* if it faulted, no need to test if the buffer was corrupted */
+ if (ret)
+ return NULL;
+
+ /*
+ * Preemption is disabled again, now check the per CPU context
+ * switch counter. If it doesn't match, then another user space
+ * process may have schedule in and corrupted our buffer. In that
+ * case the copying must be retried.
+ */
+ } while (nr_context_switches_cpu(cpu) != cnt);
+
+ *read_size = size;
+ return buffer;
+}
+
static ssize_t
tracing_mark_write(struct file *filp, const char __user *ubuf,
size_t cnt, loff_t *fpos)
@@ -7250,6 +7389,8 @@ tracing_mark_write(struct file *filp, const char __user *ubuf,
struct trace_array *tr = filp->private_data;
ssize_t written = -ENODEV;
unsigned long ip;
+ size_t size;
+ char *buf;
if (tracing_disabled)
return -EINVAL;
@@ -7263,6 +7404,16 @@ tracing_mark_write(struct file *filp, const char __user *ubuf,
if (cnt > TRACE_MARKER_MAX_SIZE)
cnt = TRACE_MARKER_MAX_SIZE;
+ /* Must have preemption disabled while having access to the buffer */
+ guard(preempt_notrace)();
+
+ buf = trace_user_fault_read(trace_user_buffer, ubuf, cnt, &size);
+ if (!buf)
+ return -EFAULT;
+
+ if (cnt > size)
+ cnt = size;
+
/* The selftests expect this function to be the IP address */
ip = _THIS_IP_;
@@ -7270,32 +7421,27 @@ tracing_mark_write(struct file *filp, const char __user *ubuf,
if (tr == &global_trace) {
guard(rcu)();
list_for_each_entry_rcu(tr, &marker_copies, marker_list) {
- written = write_marker_to_buffer(tr, ubuf, cnt, ip);
+ written = write_marker_to_buffer(tr, buf, cnt, ip);
if (written < 0)
break;
}
} else {
- written = write_marker_to_buffer(tr, ubuf, cnt, ip);
+ written = write_marker_to_buffer(tr, buf, cnt, ip);
}
return written;
}
static ssize_t write_raw_marker_to_buffer(struct trace_array *tr,
- const char __user *ubuf, size_t cnt)
+ const char *buf, size_t cnt)
{
struct ring_buffer_event *event;
struct trace_buffer *buffer;
struct raw_data_entry *entry;
ssize_t written;
- int size;
- int len;
-
-#define FAULT_SIZE_ID (FAULTED_SIZE + sizeof(int))
+ size_t size;
size = sizeof(*entry) + cnt;
- if (cnt < FAULT_SIZE_ID)
- size += FAULT_SIZE_ID - cnt;
buffer = tr->array_buffer.buffer;
@@ -7309,14 +7455,8 @@ static ssize_t write_raw_marker_to_buffer(struct trace_array *tr,
return -EBADF;
entry = ring_buffer_event_data(event);
-
- len = copy_from_user_nofault(&entry->id, ubuf, cnt);
- if (len) {
- entry->id = -1;
- memcpy(&entry->buf, FAULTED_STR, FAULTED_SIZE);
- written = -EFAULT;
- } else
- written = cnt;
+ memcpy(&entry->id, buf, cnt);
+ written = cnt;
__buffer_unlock_commit(buffer, event);
@@ -7329,8 +7469,8 @@ tracing_mark_raw_write(struct file *filp, const char __user *ubuf,
{
struct trace_array *tr = filp->private_data;
ssize_t written = -ENODEV;
-
-#define FAULT_SIZE_ID (FAULTED_SIZE + sizeof(int))
+ size_t size;
+ char *buf;
if (tracing_disabled)
return -EINVAL;
@@ -7342,6 +7482,17 @@ tracing_mark_raw_write(struct file *filp, const char __user *ubuf,
if (cnt < sizeof(unsigned int))
return -EINVAL;
+ /* Must have preemption disabled while having access to the buffer */
+ guard(preempt_notrace)();
+
+ buf = trace_user_fault_read(trace_user_buffer, ubuf, cnt, &size);
+ if (!buf)
+ return -EFAULT;
+
+ /* raw write is all or nothing */
+ if (cnt > size)
+ return -EINVAL;
+
/* The global trace_marker_raw can go to multiple instances */
if (tr == &global_trace) {
guard(rcu)();
@@ -7357,6 +7508,27 @@ tracing_mark_raw_write(struct file *filp, const char __user *ubuf,
return written;
}
+static int tracing_mark_open(struct inode *inode, struct file *filp)
+{
+ int ret;
+
+ ret = trace_user_fault_buffer_enable();
+ if (ret < 0)
+ return ret;
+
+ stream_open(inode, filp);
+ ret = tracing_open_generic_tr(inode, filp);
+ if (ret < 0)
+ trace_user_fault_buffer_disable();
+ return ret;
+}
+
+static int tracing_mark_release(struct inode *inode, struct file *file)
+{
+ trace_user_fault_buffer_disable();
+ return tracing_release_generic_tr(inode, file);
+}
+
static int tracing_clock_show(struct seq_file *m, void *v)
{
struct trace_array *tr = m->private;
@@ -7764,13 +7936,13 @@ static const struct file_operations tracing_free_buffer_fops = {
static const struct file_operations tracing_mark_fops = {
.open = tracing_mark_open,
.write = tracing_mark_write,
- .release = tracing_release_generic_tr,
+ .release = tracing_mark_release,
};
static const struct file_operations tracing_mark_raw_fops = {
.open = tracing_mark_open,
.write = tracing_mark_raw_write,
- .release = tracing_release_generic_tr,
+ .release = tracing_mark_release,
};
static const struct file_operations trace_clock_fops = {
The patch below does not apply to the 6.1-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable(a)vger.kernel.org>.
To reproduce the conflict and resubmit, you may use the following commands:
git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.1.y
git checkout FETCH_HEAD
git cherry-pick -x 64cf7d058a005c5c31eb8a0b741f35dc12915d18
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2025101300-unburned-stage-ee62@gregkh' --subject-prefix 'PATCH 6.1.y' HEAD^..
Possible dependencies:
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From 64cf7d058a005c5c31eb8a0b741f35dc12915d18 Mon Sep 17 00:00:00 2001
From: Steven Rostedt <rostedt(a)goodmis.org>
Date: Wed, 8 Oct 2025 12:45:10 -0400
Subject: [PATCH] tracing: Have trace_marker use per-cpu data to read user
space
It was reported that using __copy_from_user_inatomic() can actually
schedule. Which is bad when preemption is disabled. Even though there's
logic to check in_atomic() is set, but this is a nop when the kernel is
configured with PREEMPT_NONE. This is due to page faulting and the code
could schedule with preemption disabled.
Link: https://lore.kernel.org/all/20250819105152.2766363-1-luogengkun@huaweicloud…
The solution was to change the __copy_from_user_inatomic() to
copy_from_user_nofault(). But then it was reported that this caused a
regression in Android. There's several applications writing into
trace_marker() in Android, but now instead of showing the expected data,
it is showing:
tracing_mark_write: <faulted>
After reverting the conversion to copy_from_user_nofault(), Android was
able to get the data again.
Writes to the trace_marker is a way to efficiently and quickly enter data
into the Linux tracing buffer. It takes no locks and was designed to be as
non-intrusive as possible. This means it cannot allocate memory, and must
use pre-allocated data.
A method that is actively being worked on to have faultable system call
tracepoints read user space data is to allocate per CPU buffers, and use
them in the callback. The method uses a technique similar to seqcount.
That is something like this:
preempt_disable();
cpu = smp_processor_id();
buffer = this_cpu_ptr(&pre_allocated_cpu_buffers, cpu);
do {
cnt = nr_context_switches_cpu(cpu);
migrate_disable();
preempt_enable();
ret = copy_from_user(buffer, ptr, size);
preempt_disable();
migrate_enable();
} while (!ret && cnt != nr_context_switches_cpu(cpu));
if (!ret)
ring_buffer_write(buffer);
preempt_enable();
It's a little more involved than that, but the above is the basic logic.
The idea is to acquire the current CPU buffer, disable migration, and then
enable preemption. At this moment, it can safely use copy_from_user().
After reading the data from user space, it disables preemption again. It
then checks to see if there was any new scheduling on this CPU. If there
was, it must assume that the buffer was corrupted by another task. If
there wasn't, then the buffer is still valid as only tasks in preemptable
context can write to this buffer and only those that are running on the
CPU.
By using this method, where trace_marker open allocates the per CPU
buffers, trace_marker writes can access user space and even fault it in,
without having to allocate or take any locks of its own.
Cc: stable(a)vger.kernel.org
Cc: Masami Hiramatsu <mhiramat(a)kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers(a)efficios.com>
Cc: Luo Gengkun <luogengkun(a)huaweicloud.com>
Cc: Wattson CI <wattson-external(a)google.com>
Cc: Linus Torvalds <torvalds(a)linux-foundation.org>
Link: https://lore.kernel.org/20251008124510.6dba541a@gandalf.local.home
Fixes: 3d62ab32df065 ("tracing: Fix tracing_marker may trigger page fault during preempt_disable")
Reported-by: Runping Lai <runpinglai(a)google.com>
Tested-by: Runping Lai <runpinglai(a)google.com>
Closes: https://lore.kernel.org/linux-trace-kernel/20251007003417.3470979-2-runping…
Signed-off-by: Steven Rostedt (Google) <rostedt(a)goodmis.org>
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index b3c94fbaf002..0fd582651293 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -4791,12 +4791,6 @@ int tracing_single_release_file_tr(struct inode *inode, struct file *filp)
return single_release(inode, filp);
}
-static int tracing_mark_open(struct inode *inode, struct file *filp)
-{
- stream_open(inode, filp);
- return tracing_open_generic_tr(inode, filp);
-}
-
static int tracing_release(struct inode *inode, struct file *file)
{
struct trace_array *tr = inode->i_private;
@@ -7163,7 +7157,7 @@ tracing_free_buffer_release(struct inode *inode, struct file *filp)
#define TRACE_MARKER_MAX_SIZE 4096
-static ssize_t write_marker_to_buffer(struct trace_array *tr, const char __user *ubuf,
+static ssize_t write_marker_to_buffer(struct trace_array *tr, const char *buf,
size_t cnt, unsigned long ip)
{
struct ring_buffer_event *event;
@@ -7173,20 +7167,11 @@ static ssize_t write_marker_to_buffer(struct trace_array *tr, const char __user
int meta_size;
ssize_t written;
size_t size;
- int len;
-
-/* Used in tracing_mark_raw_write() as well */
-#define FAULTED_STR "<faulted>"
-#define FAULTED_SIZE (sizeof(FAULTED_STR) - 1) /* '\0' is already accounted for */
meta_size = sizeof(*entry) + 2; /* add '\0' and possible '\n' */
again:
size = cnt + meta_size;
- /* If less than "<faulted>", then make sure we can still add that */
- if (cnt < FAULTED_SIZE)
- size += FAULTED_SIZE - cnt;
-
buffer = tr->array_buffer.buffer;
event = __trace_buffer_lock_reserve(buffer, TRACE_PRINT, size,
tracing_gen_ctx());
@@ -7196,9 +7181,6 @@ static ssize_t write_marker_to_buffer(struct trace_array *tr, const char __user
* make it smaller and try again.
*/
if (size > ring_buffer_max_event_size(buffer)) {
- /* cnt < FAULTED size should never be bigger than max */
- if (WARN_ON_ONCE(cnt < FAULTED_SIZE))
- return -EBADF;
cnt = ring_buffer_max_event_size(buffer) - meta_size;
/* The above should only happen once */
if (WARN_ON_ONCE(cnt + meta_size == size))
@@ -7212,14 +7194,8 @@ static ssize_t write_marker_to_buffer(struct trace_array *tr, const char __user
entry = ring_buffer_event_data(event);
entry->ip = ip;
-
- len = copy_from_user_nofault(&entry->buf, ubuf, cnt);
- if (len) {
- memcpy(&entry->buf, FAULTED_STR, FAULTED_SIZE);
- cnt = FAULTED_SIZE;
- written = -EFAULT;
- } else
- written = cnt;
+ memcpy(&entry->buf, buf, cnt);
+ written = cnt;
if (tr->trace_marker_file && !list_empty(&tr->trace_marker_file->triggers)) {
/* do not add \n before testing triggers, but add \0 */
@@ -7243,6 +7219,169 @@ static ssize_t write_marker_to_buffer(struct trace_array *tr, const char __user
return written;
}
+struct trace_user_buf {
+ char *buf;
+};
+
+struct trace_user_buf_info {
+ struct trace_user_buf __percpu *tbuf;
+ int ref;
+};
+
+
+static DEFINE_MUTEX(trace_user_buffer_mutex);
+static struct trace_user_buf_info *trace_user_buffer;
+
+static void trace_user_fault_buffer_free(struct trace_user_buf_info *tinfo)
+{
+ char *buf;
+ int cpu;
+
+ for_each_possible_cpu(cpu) {
+ buf = per_cpu_ptr(tinfo->tbuf, cpu)->buf;
+ kfree(buf);
+ }
+ free_percpu(tinfo->tbuf);
+ kfree(tinfo);
+}
+
+static int trace_user_fault_buffer_enable(void)
+{
+ struct trace_user_buf_info *tinfo;
+ char *buf;
+ int cpu;
+
+ guard(mutex)(&trace_user_buffer_mutex);
+
+ if (trace_user_buffer) {
+ trace_user_buffer->ref++;
+ return 0;
+ }
+
+ tinfo = kmalloc(sizeof(*tinfo), GFP_KERNEL);
+ if (!tinfo)
+ return -ENOMEM;
+
+ tinfo->tbuf = alloc_percpu(struct trace_user_buf);
+ if (!tinfo->tbuf) {
+ kfree(tinfo);
+ return -ENOMEM;
+ }
+
+ tinfo->ref = 1;
+
+ /* Clear each buffer in case of error */
+ for_each_possible_cpu(cpu) {
+ per_cpu_ptr(tinfo->tbuf, cpu)->buf = NULL;
+ }
+
+ for_each_possible_cpu(cpu) {
+ buf = kmalloc_node(TRACE_MARKER_MAX_SIZE, GFP_KERNEL,
+ cpu_to_node(cpu));
+ if (!buf) {
+ trace_user_fault_buffer_free(tinfo);
+ return -ENOMEM;
+ }
+ per_cpu_ptr(tinfo->tbuf, cpu)->buf = buf;
+ }
+
+ trace_user_buffer = tinfo;
+
+ return 0;
+}
+
+static void trace_user_fault_buffer_disable(void)
+{
+ struct trace_user_buf_info *tinfo;
+
+ guard(mutex)(&trace_user_buffer_mutex);
+
+ tinfo = trace_user_buffer;
+
+ if (WARN_ON_ONCE(!tinfo))
+ return;
+
+ if (--tinfo->ref)
+ return;
+
+ trace_user_fault_buffer_free(tinfo);
+ trace_user_buffer = NULL;
+}
+
+/* Must be called with preemption disabled */
+static char *trace_user_fault_read(struct trace_user_buf_info *tinfo,
+ const char __user *ptr, size_t size,
+ size_t *read_size)
+{
+ int cpu = smp_processor_id();
+ char *buffer = per_cpu_ptr(tinfo->tbuf, cpu)->buf;
+ unsigned int cnt;
+ int trys = 0;
+ int ret;
+
+ if (size > TRACE_MARKER_MAX_SIZE)
+ size = TRACE_MARKER_MAX_SIZE;
+ *read_size = 0;
+
+ /*
+ * This acts similar to a seqcount. The per CPU context switches are
+ * recorded, migration is disabled and preemption is enabled. The
+ * read of the user space memory is copied into the per CPU buffer.
+ * Preemption is disabled again, and if the per CPU context switches count
+ * is still the same, it means the buffer has not been corrupted.
+ * If the count is different, it is assumed the buffer is corrupted
+ * and reading must be tried again.
+ */
+
+ do {
+ /*
+ * If for some reason, copy_from_user() always causes a context
+ * switch, this would then cause an infinite loop.
+ * If this task is preempted by another user space task, it
+ * will cause this task to try again. But just in case something
+ * changes where the copying from user space causes another task
+ * to run, prevent this from going into an infinite loop.
+ * 100 tries should be plenty.
+ */
+ if (WARN_ONCE(trys++ > 100, "Error: Too many tries to read user space"))
+ return NULL;
+
+ /* Read the current CPU context switch counter */
+ cnt = nr_context_switches_cpu(cpu);
+
+ /*
+ * Preemption is going to be enabled, but this task must
+ * remain on this CPU.
+ */
+ migrate_disable();
+
+ /*
+ * Now preemption is being enabed and another task can come in
+ * and use the same buffer and corrupt our data.
+ */
+ preempt_enable_notrace();
+
+ ret = __copy_from_user(buffer, ptr, size);
+
+ preempt_disable_notrace();
+ migrate_enable();
+
+ /* if it faulted, no need to test if the buffer was corrupted */
+ if (ret)
+ return NULL;
+
+ /*
+ * Preemption is disabled again, now check the per CPU context
+ * switch counter. If it doesn't match, then another user space
+ * process may have schedule in and corrupted our buffer. In that
+ * case the copying must be retried.
+ */
+ } while (nr_context_switches_cpu(cpu) != cnt);
+
+ *read_size = size;
+ return buffer;
+}
+
static ssize_t
tracing_mark_write(struct file *filp, const char __user *ubuf,
size_t cnt, loff_t *fpos)
@@ -7250,6 +7389,8 @@ tracing_mark_write(struct file *filp, const char __user *ubuf,
struct trace_array *tr = filp->private_data;
ssize_t written = -ENODEV;
unsigned long ip;
+ size_t size;
+ char *buf;
if (tracing_disabled)
return -EINVAL;
@@ -7263,6 +7404,16 @@ tracing_mark_write(struct file *filp, const char __user *ubuf,
if (cnt > TRACE_MARKER_MAX_SIZE)
cnt = TRACE_MARKER_MAX_SIZE;
+ /* Must have preemption disabled while having access to the buffer */
+ guard(preempt_notrace)();
+
+ buf = trace_user_fault_read(trace_user_buffer, ubuf, cnt, &size);
+ if (!buf)
+ return -EFAULT;
+
+ if (cnt > size)
+ cnt = size;
+
/* The selftests expect this function to be the IP address */
ip = _THIS_IP_;
@@ -7270,32 +7421,27 @@ tracing_mark_write(struct file *filp, const char __user *ubuf,
if (tr == &global_trace) {
guard(rcu)();
list_for_each_entry_rcu(tr, &marker_copies, marker_list) {
- written = write_marker_to_buffer(tr, ubuf, cnt, ip);
+ written = write_marker_to_buffer(tr, buf, cnt, ip);
if (written < 0)
break;
}
} else {
- written = write_marker_to_buffer(tr, ubuf, cnt, ip);
+ written = write_marker_to_buffer(tr, buf, cnt, ip);
}
return written;
}
static ssize_t write_raw_marker_to_buffer(struct trace_array *tr,
- const char __user *ubuf, size_t cnt)
+ const char *buf, size_t cnt)
{
struct ring_buffer_event *event;
struct trace_buffer *buffer;
struct raw_data_entry *entry;
ssize_t written;
- int size;
- int len;
-
-#define FAULT_SIZE_ID (FAULTED_SIZE + sizeof(int))
+ size_t size;
size = sizeof(*entry) + cnt;
- if (cnt < FAULT_SIZE_ID)
- size += FAULT_SIZE_ID - cnt;
buffer = tr->array_buffer.buffer;
@@ -7309,14 +7455,8 @@ static ssize_t write_raw_marker_to_buffer(struct trace_array *tr,
return -EBADF;
entry = ring_buffer_event_data(event);
-
- len = copy_from_user_nofault(&entry->id, ubuf, cnt);
- if (len) {
- entry->id = -1;
- memcpy(&entry->buf, FAULTED_STR, FAULTED_SIZE);
- written = -EFAULT;
- } else
- written = cnt;
+ memcpy(&entry->id, buf, cnt);
+ written = cnt;
__buffer_unlock_commit(buffer, event);
@@ -7329,8 +7469,8 @@ tracing_mark_raw_write(struct file *filp, const char __user *ubuf,
{
struct trace_array *tr = filp->private_data;
ssize_t written = -ENODEV;
-
-#define FAULT_SIZE_ID (FAULTED_SIZE + sizeof(int))
+ size_t size;
+ char *buf;
if (tracing_disabled)
return -EINVAL;
@@ -7342,6 +7482,17 @@ tracing_mark_raw_write(struct file *filp, const char __user *ubuf,
if (cnt < sizeof(unsigned int))
return -EINVAL;
+ /* Must have preemption disabled while having access to the buffer */
+ guard(preempt_notrace)();
+
+ buf = trace_user_fault_read(trace_user_buffer, ubuf, cnt, &size);
+ if (!buf)
+ return -EFAULT;
+
+ /* raw write is all or nothing */
+ if (cnt > size)
+ return -EINVAL;
+
/* The global trace_marker_raw can go to multiple instances */
if (tr == &global_trace) {
guard(rcu)();
@@ -7357,6 +7508,27 @@ tracing_mark_raw_write(struct file *filp, const char __user *ubuf,
return written;
}
+static int tracing_mark_open(struct inode *inode, struct file *filp)
+{
+ int ret;
+
+ ret = trace_user_fault_buffer_enable();
+ if (ret < 0)
+ return ret;
+
+ stream_open(inode, filp);
+ ret = tracing_open_generic_tr(inode, filp);
+ if (ret < 0)
+ trace_user_fault_buffer_disable();
+ return ret;
+}
+
+static int tracing_mark_release(struct inode *inode, struct file *file)
+{
+ trace_user_fault_buffer_disable();
+ return tracing_release_generic_tr(inode, file);
+}
+
static int tracing_clock_show(struct seq_file *m, void *v)
{
struct trace_array *tr = m->private;
@@ -7764,13 +7936,13 @@ static const struct file_operations tracing_free_buffer_fops = {
static const struct file_operations tracing_mark_fops = {
.open = tracing_mark_open,
.write = tracing_mark_write,
- .release = tracing_release_generic_tr,
+ .release = tracing_mark_release,
};
static const struct file_operations tracing_mark_raw_fops = {
.open = tracing_mark_open,
.write = tracing_mark_raw_write,
- .release = tracing_release_generic_tr,
+ .release = tracing_mark_release,
};
static const struct file_operations trace_clock_fops = {
The patch below does not apply to the 6.6-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable(a)vger.kernel.org>.
To reproduce the conflict and resubmit, you may use the following commands:
git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.6.y
git checkout FETCH_HEAD
git cherry-pick -x 64cf7d058a005c5c31eb8a0b741f35dc12915d18
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2025101357-tremble-silenced-1049@gregkh' --subject-prefix 'PATCH 6.6.y' HEAD^..
Possible dependencies:
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From 64cf7d058a005c5c31eb8a0b741f35dc12915d18 Mon Sep 17 00:00:00 2001
From: Steven Rostedt <rostedt(a)goodmis.org>
Date: Wed, 8 Oct 2025 12:45:10 -0400
Subject: [PATCH] tracing: Have trace_marker use per-cpu data to read user
space
It was reported that using __copy_from_user_inatomic() can actually
schedule. Which is bad when preemption is disabled. Even though there's
logic to check in_atomic() is set, but this is a nop when the kernel is
configured with PREEMPT_NONE. This is due to page faulting and the code
could schedule with preemption disabled.
Link: https://lore.kernel.org/all/20250819105152.2766363-1-luogengkun@huaweicloud…
The solution was to change the __copy_from_user_inatomic() to
copy_from_user_nofault(). But then it was reported that this caused a
regression in Android. There's several applications writing into
trace_marker() in Android, but now instead of showing the expected data,
it is showing:
tracing_mark_write: <faulted>
After reverting the conversion to copy_from_user_nofault(), Android was
able to get the data again.
Writes to the trace_marker is a way to efficiently and quickly enter data
into the Linux tracing buffer. It takes no locks and was designed to be as
non-intrusive as possible. This means it cannot allocate memory, and must
use pre-allocated data.
A method that is actively being worked on to have faultable system call
tracepoints read user space data is to allocate per CPU buffers, and use
them in the callback. The method uses a technique similar to seqcount.
That is something like this:
preempt_disable();
cpu = smp_processor_id();
buffer = this_cpu_ptr(&pre_allocated_cpu_buffers, cpu);
do {
cnt = nr_context_switches_cpu(cpu);
migrate_disable();
preempt_enable();
ret = copy_from_user(buffer, ptr, size);
preempt_disable();
migrate_enable();
} while (!ret && cnt != nr_context_switches_cpu(cpu));
if (!ret)
ring_buffer_write(buffer);
preempt_enable();
It's a little more involved than that, but the above is the basic logic.
The idea is to acquire the current CPU buffer, disable migration, and then
enable preemption. At this moment, it can safely use copy_from_user().
After reading the data from user space, it disables preemption again. It
then checks to see if there was any new scheduling on this CPU. If there
was, it must assume that the buffer was corrupted by another task. If
there wasn't, then the buffer is still valid as only tasks in preemptable
context can write to this buffer and only those that are running on the
CPU.
By using this method, where trace_marker open allocates the per CPU
buffers, trace_marker writes can access user space and even fault it in,
without having to allocate or take any locks of its own.
Cc: stable(a)vger.kernel.org
Cc: Masami Hiramatsu <mhiramat(a)kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers(a)efficios.com>
Cc: Luo Gengkun <luogengkun(a)huaweicloud.com>
Cc: Wattson CI <wattson-external(a)google.com>
Cc: Linus Torvalds <torvalds(a)linux-foundation.org>
Link: https://lore.kernel.org/20251008124510.6dba541a@gandalf.local.home
Fixes: 3d62ab32df065 ("tracing: Fix tracing_marker may trigger page fault during preempt_disable")
Reported-by: Runping Lai <runpinglai(a)google.com>
Tested-by: Runping Lai <runpinglai(a)google.com>
Closes: https://lore.kernel.org/linux-trace-kernel/20251007003417.3470979-2-runping…
Signed-off-by: Steven Rostedt (Google) <rostedt(a)goodmis.org>
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index b3c94fbaf002..0fd582651293 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -4791,12 +4791,6 @@ int tracing_single_release_file_tr(struct inode *inode, struct file *filp)
return single_release(inode, filp);
}
-static int tracing_mark_open(struct inode *inode, struct file *filp)
-{
- stream_open(inode, filp);
- return tracing_open_generic_tr(inode, filp);
-}
-
static int tracing_release(struct inode *inode, struct file *file)
{
struct trace_array *tr = inode->i_private;
@@ -7163,7 +7157,7 @@ tracing_free_buffer_release(struct inode *inode, struct file *filp)
#define TRACE_MARKER_MAX_SIZE 4096
-static ssize_t write_marker_to_buffer(struct trace_array *tr, const char __user *ubuf,
+static ssize_t write_marker_to_buffer(struct trace_array *tr, const char *buf,
size_t cnt, unsigned long ip)
{
struct ring_buffer_event *event;
@@ -7173,20 +7167,11 @@ static ssize_t write_marker_to_buffer(struct trace_array *tr, const char __user
int meta_size;
ssize_t written;
size_t size;
- int len;
-
-/* Used in tracing_mark_raw_write() as well */
-#define FAULTED_STR "<faulted>"
-#define FAULTED_SIZE (sizeof(FAULTED_STR) - 1) /* '\0' is already accounted for */
meta_size = sizeof(*entry) + 2; /* add '\0' and possible '\n' */
again:
size = cnt + meta_size;
- /* If less than "<faulted>", then make sure we can still add that */
- if (cnt < FAULTED_SIZE)
- size += FAULTED_SIZE - cnt;
-
buffer = tr->array_buffer.buffer;
event = __trace_buffer_lock_reserve(buffer, TRACE_PRINT, size,
tracing_gen_ctx());
@@ -7196,9 +7181,6 @@ static ssize_t write_marker_to_buffer(struct trace_array *tr, const char __user
* make it smaller and try again.
*/
if (size > ring_buffer_max_event_size(buffer)) {
- /* cnt < FAULTED size should never be bigger than max */
- if (WARN_ON_ONCE(cnt < FAULTED_SIZE))
- return -EBADF;
cnt = ring_buffer_max_event_size(buffer) - meta_size;
/* The above should only happen once */
if (WARN_ON_ONCE(cnt + meta_size == size))
@@ -7212,14 +7194,8 @@ static ssize_t write_marker_to_buffer(struct trace_array *tr, const char __user
entry = ring_buffer_event_data(event);
entry->ip = ip;
-
- len = copy_from_user_nofault(&entry->buf, ubuf, cnt);
- if (len) {
- memcpy(&entry->buf, FAULTED_STR, FAULTED_SIZE);
- cnt = FAULTED_SIZE;
- written = -EFAULT;
- } else
- written = cnt;
+ memcpy(&entry->buf, buf, cnt);
+ written = cnt;
if (tr->trace_marker_file && !list_empty(&tr->trace_marker_file->triggers)) {
/* do not add \n before testing triggers, but add \0 */
@@ -7243,6 +7219,169 @@ static ssize_t write_marker_to_buffer(struct trace_array *tr, const char __user
return written;
}
+struct trace_user_buf {
+ char *buf;
+};
+
+struct trace_user_buf_info {
+ struct trace_user_buf __percpu *tbuf;
+ int ref;
+};
+
+
+static DEFINE_MUTEX(trace_user_buffer_mutex);
+static struct trace_user_buf_info *trace_user_buffer;
+
+static void trace_user_fault_buffer_free(struct trace_user_buf_info *tinfo)
+{
+ char *buf;
+ int cpu;
+
+ for_each_possible_cpu(cpu) {
+ buf = per_cpu_ptr(tinfo->tbuf, cpu)->buf;
+ kfree(buf);
+ }
+ free_percpu(tinfo->tbuf);
+ kfree(tinfo);
+}
+
+static int trace_user_fault_buffer_enable(void)
+{
+ struct trace_user_buf_info *tinfo;
+ char *buf;
+ int cpu;
+
+ guard(mutex)(&trace_user_buffer_mutex);
+
+ if (trace_user_buffer) {
+ trace_user_buffer->ref++;
+ return 0;
+ }
+
+ tinfo = kmalloc(sizeof(*tinfo), GFP_KERNEL);
+ if (!tinfo)
+ return -ENOMEM;
+
+ tinfo->tbuf = alloc_percpu(struct trace_user_buf);
+ if (!tinfo->tbuf) {
+ kfree(tinfo);
+ return -ENOMEM;
+ }
+
+ tinfo->ref = 1;
+
+ /* Clear each buffer in case of error */
+ for_each_possible_cpu(cpu) {
+ per_cpu_ptr(tinfo->tbuf, cpu)->buf = NULL;
+ }
+
+ for_each_possible_cpu(cpu) {
+ buf = kmalloc_node(TRACE_MARKER_MAX_SIZE, GFP_KERNEL,
+ cpu_to_node(cpu));
+ if (!buf) {
+ trace_user_fault_buffer_free(tinfo);
+ return -ENOMEM;
+ }
+ per_cpu_ptr(tinfo->tbuf, cpu)->buf = buf;
+ }
+
+ trace_user_buffer = tinfo;
+
+ return 0;
+}
+
+static void trace_user_fault_buffer_disable(void)
+{
+ struct trace_user_buf_info *tinfo;
+
+ guard(mutex)(&trace_user_buffer_mutex);
+
+ tinfo = trace_user_buffer;
+
+ if (WARN_ON_ONCE(!tinfo))
+ return;
+
+ if (--tinfo->ref)
+ return;
+
+ trace_user_fault_buffer_free(tinfo);
+ trace_user_buffer = NULL;
+}
+
+/* Must be called with preemption disabled */
+static char *trace_user_fault_read(struct trace_user_buf_info *tinfo,
+ const char __user *ptr, size_t size,
+ size_t *read_size)
+{
+ int cpu = smp_processor_id();
+ char *buffer = per_cpu_ptr(tinfo->tbuf, cpu)->buf;
+ unsigned int cnt;
+ int trys = 0;
+ int ret;
+
+ if (size > TRACE_MARKER_MAX_SIZE)
+ size = TRACE_MARKER_MAX_SIZE;
+ *read_size = 0;
+
+ /*
+ * This acts similar to a seqcount. The per CPU context switches are
+ * recorded, migration is disabled and preemption is enabled. The
+ * read of the user space memory is copied into the per CPU buffer.
+ * Preemption is disabled again, and if the per CPU context switches count
+ * is still the same, it means the buffer has not been corrupted.
+ * If the count is different, it is assumed the buffer is corrupted
+ * and reading must be tried again.
+ */
+
+ do {
+ /*
+ * If for some reason, copy_from_user() always causes a context
+ * switch, this would then cause an infinite loop.
+ * If this task is preempted by another user space task, it
+ * will cause this task to try again. But just in case something
+ * changes where the copying from user space causes another task
+ * to run, prevent this from going into an infinite loop.
+ * 100 tries should be plenty.
+ */
+ if (WARN_ONCE(trys++ > 100, "Error: Too many tries to read user space"))
+ return NULL;
+
+ /* Read the current CPU context switch counter */
+ cnt = nr_context_switches_cpu(cpu);
+
+ /*
+ * Preemption is going to be enabled, but this task must
+ * remain on this CPU.
+ */
+ migrate_disable();
+
+ /*
+ * Now preemption is being enabed and another task can come in
+ * and use the same buffer and corrupt our data.
+ */
+ preempt_enable_notrace();
+
+ ret = __copy_from_user(buffer, ptr, size);
+
+ preempt_disable_notrace();
+ migrate_enable();
+
+ /* if it faulted, no need to test if the buffer was corrupted */
+ if (ret)
+ return NULL;
+
+ /*
+ * Preemption is disabled again, now check the per CPU context
+ * switch counter. If it doesn't match, then another user space
+ * process may have schedule in and corrupted our buffer. In that
+ * case the copying must be retried.
+ */
+ } while (nr_context_switches_cpu(cpu) != cnt);
+
+ *read_size = size;
+ return buffer;
+}
+
static ssize_t
tracing_mark_write(struct file *filp, const char __user *ubuf,
size_t cnt, loff_t *fpos)
@@ -7250,6 +7389,8 @@ tracing_mark_write(struct file *filp, const char __user *ubuf,
struct trace_array *tr = filp->private_data;
ssize_t written = -ENODEV;
unsigned long ip;
+ size_t size;
+ char *buf;
if (tracing_disabled)
return -EINVAL;
@@ -7263,6 +7404,16 @@ tracing_mark_write(struct file *filp, const char __user *ubuf,
if (cnt > TRACE_MARKER_MAX_SIZE)
cnt = TRACE_MARKER_MAX_SIZE;
+ /* Must have preemption disabled while having access to the buffer */
+ guard(preempt_notrace)();
+
+ buf = trace_user_fault_read(trace_user_buffer, ubuf, cnt, &size);
+ if (!buf)
+ return -EFAULT;
+
+ if (cnt > size)
+ cnt = size;
+
/* The selftests expect this function to be the IP address */
ip = _THIS_IP_;
@@ -7270,32 +7421,27 @@ tracing_mark_write(struct file *filp, const char __user *ubuf,
if (tr == &global_trace) {
guard(rcu)();
list_for_each_entry_rcu(tr, &marker_copies, marker_list) {
- written = write_marker_to_buffer(tr, ubuf, cnt, ip);
+ written = write_marker_to_buffer(tr, buf, cnt, ip);
if (written < 0)
break;
}
} else {
- written = write_marker_to_buffer(tr, ubuf, cnt, ip);
+ written = write_marker_to_buffer(tr, buf, cnt, ip);
}
return written;
}
static ssize_t write_raw_marker_to_buffer(struct trace_array *tr,
- const char __user *ubuf, size_t cnt)
+ const char *buf, size_t cnt)
{
struct ring_buffer_event *event;
struct trace_buffer *buffer;
struct raw_data_entry *entry;
ssize_t written;
- int size;
- int len;
-
-#define FAULT_SIZE_ID (FAULTED_SIZE + sizeof(int))
+ size_t size;
size = sizeof(*entry) + cnt;
- if (cnt < FAULT_SIZE_ID)
- size += FAULT_SIZE_ID - cnt;
buffer = tr->array_buffer.buffer;
@@ -7309,14 +7455,8 @@ static ssize_t write_raw_marker_to_buffer(struct trace_array *tr,
return -EBADF;
entry = ring_buffer_event_data(event);
-
- len = copy_from_user_nofault(&entry->id, ubuf, cnt);
- if (len) {
- entry->id = -1;
- memcpy(&entry->buf, FAULTED_STR, FAULTED_SIZE);
- written = -EFAULT;
- } else
- written = cnt;
+ memcpy(&entry->id, buf, cnt);
+ written = cnt;
__buffer_unlock_commit(buffer, event);
@@ -7329,8 +7469,8 @@ tracing_mark_raw_write(struct file *filp, const char __user *ubuf,
{
struct trace_array *tr = filp->private_data;
ssize_t written = -ENODEV;
-
-#define FAULT_SIZE_ID (FAULTED_SIZE + sizeof(int))
+ size_t size;
+ char *buf;
if (tracing_disabled)
return -EINVAL;
@@ -7342,6 +7482,17 @@ tracing_mark_raw_write(struct file *filp, const char __user *ubuf,
if (cnt < sizeof(unsigned int))
return -EINVAL;
+ /* Must have preemption disabled while having access to the buffer */
+ guard(preempt_notrace)();
+
+ buf = trace_user_fault_read(trace_user_buffer, ubuf, cnt, &size);
+ if (!buf)
+ return -EFAULT;
+
+ /* raw write is all or nothing */
+ if (cnt > size)
+ return -EINVAL;
+
/* The global trace_marker_raw can go to multiple instances */
if (tr == &global_trace) {
guard(rcu)();
@@ -7357,6 +7508,27 @@ tracing_mark_raw_write(struct file *filp, const char __user *ubuf,
return written;
}
+static int tracing_mark_open(struct inode *inode, struct file *filp)
+{
+ int ret;
+
+ ret = trace_user_fault_buffer_enable();
+ if (ret < 0)
+ return ret;
+
+ stream_open(inode, filp);
+ ret = tracing_open_generic_tr(inode, filp);
+ if (ret < 0)
+ trace_user_fault_buffer_disable();
+ return ret;
+}
+
+static int tracing_mark_release(struct inode *inode, struct file *file)
+{
+ trace_user_fault_buffer_disable();
+ return tracing_release_generic_tr(inode, file);
+}
+
static int tracing_clock_show(struct seq_file *m, void *v)
{
struct trace_array *tr = m->private;
@@ -7764,13 +7936,13 @@ static const struct file_operations tracing_free_buffer_fops = {
static const struct file_operations tracing_mark_fops = {
.open = tracing_mark_open,
.write = tracing_mark_write,
- .release = tracing_release_generic_tr,
+ .release = tracing_mark_release,
};
static const struct file_operations tracing_mark_raw_fops = {
.open = tracing_mark_open,
.write = tracing_mark_raw_write,
- .release = tracing_release_generic_tr,
+ .release = tracing_mark_release,
};
static const struct file_operations trace_clock_fops = {
pidfd_pid() may return an ERR_PTR() when the file does not refer to a
valid pidfs file. Currently pidfd_info() calls pid_in_current_pidns()
directly on the returned value, which risks dereferencing an ERR_PTR.
Fix it by explicitly checking IS_ERR(pid) and returning PTR_ERR(pid)
before further use.
Fixes: 7477d7dce48a ("pidfs: allow to retrieve exit information")
Cc: stable(a)vger.kernel.org
Signed-off-by: Zhen Ni <zhen.ni(a)easystack.cn>
---
fs/pidfs.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/fs/pidfs.c b/fs/pidfs.c
index 0ef5b47d796a..16670648bb09 100644
--- a/fs/pidfs.c
+++ b/fs/pidfs.c
@@ -314,6 +314,9 @@ static long pidfd_info(struct file *file, unsigned int cmd, unsigned long arg)
if (copy_from_user(&mask, &uinfo->mask, sizeof(mask)))
return -EFAULT;
+ if (IS_ERR(pid))
+ return PTR_ERR(pid);
+
/*
* Restrict information retrieval to tasks within the caller's pid
* namespace hierarchy.
--
2.20.1
Hi Sasha,
Please do NOT backport commit dd83609b8898 alone to stable. This patch
causes a regression in fallocate(PUNCH_HOLE) operations where pages are
not freed immediately, as reported by Mark Brown.
The fix for this regression is already in linux-next as commit
91a830422707 ("hugetlbfs: check for shareable lock before calling
huge_pmd_unshare()").
Please backport both commits together to avoid introducing the
regression in stable kernels:
- dd83609b88986f4add37c0871c3434310652ebd5 ("hugetlbfs: skip VMAs without shareable locks in hugetlb_vmdelete_list")
- 91a830422707a62629fc4fbf8cdc3c8acf56ca64 ("hugetlbfs: check for shareable lock before calling huge_pmd_unshare()")
Thanks,
Deepanshu Kartikey
The function lan78xx_write_raw_eeprom failed to properly propagate EEPROM
write timeout errors (-ETIMEDOUT). In the timeout fallthrough path, it first
attempted to restore the pin configuration for LED outputs and then
returned only the status of that restore operation, discarding the
original timeout error saved in ret.
As a result, callers could mistakenly treat EEPROM write operation as
successful even though the EEPROM write had actually timed out with no
or partial data write.
To fix this, handle errors in restoring the LED pin configuration separately.
If the restore succeeds, return any prior EEPROM write timeout error saved
in ret to the caller.
Suggested-by: Oleksij Rempel <o.rempel(a)pengutronix.de>
Fixes: 8b1b2ca83b20 ("net: usb: lan78xx: Improve error handling in EEPROM and OTP operations")
cc: stable(a)vger.kernel.org
Signed-off-by: Bhanu Seshu Kumar Valluri <bhanuseshukumar(a)gmail.com>
---
Note:
The patch is compiled and tested using EVB-LAN7800LC.
The patch was suggested by Oleksij Rempel while reviewing a fix to a bug
found by syzbot earlier.
The review mail chain where this fix was suggested is given below.
https://lore.kernel.org/all/aNzojoXK-m1Tn6Lc@pengutronix.de/
ChangeLog:
v1->v2:
Added cc:stable tag as asked during v1 review.
V1 Link : https://lore.kernel.org/all/20251004040722.82882-1-bhanuseshukumar@gmail.co…
drivers/net/usb/lan78xx.c | 11 +++++++----
1 file changed, 7 insertions(+), 4 deletions(-)
diff --git a/drivers/net/usb/lan78xx.c b/drivers/net/usb/lan78xx.c
index d75502ebbc0d..5ccbe6ae2ebe 100644
--- a/drivers/net/usb/lan78xx.c
+++ b/drivers/net/usb/lan78xx.c
@@ -1174,10 +1174,13 @@ static int lan78xx_write_raw_eeprom(struct lan78xx_net *dev, u32 offset,
}
write_raw_eeprom_done:
- if (dev->chipid == ID_REV_CHIP_ID_7800_)
- return lan78xx_write_reg(dev, HW_CFG, saved);
-
- return 0;
+ if (dev->chipid == ID_REV_CHIP_ID_7800_) {
+ int rc = lan78xx_write_reg(dev, HW_CFG, saved);
+ /* If USB fails, there is nothing to do */
+ if (rc < 0)
+ return rc;
+ }
+ return ret;
}
static int lan78xx_read_raw_otp(struct lan78xx_net *dev, u32 offset,
--
2.34.1
On October 12, 2025 7:20:16 AM PDT, Sasha Levin <sashal(a)kernel.org> wrote:
>This is a note to let you know that I've just added the patch titled
>
> x86/vdso: Fix output operand size of RDPID
>
>to the 6.16-stable tree which can be found at:
> http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=sum…
>
>The filename of the patch is:
> x86-vdso-fix-output-operand-size-of-rdpid.patch
>and it can be found in the queue-6.16 subdirectory.
>
>If you, or anyone else, feels it should not be added to the stable tree,
>please let <stable(a)vger.kernel.org> know about it.
>
>
>
>commit 9e09c5e5e76f1bb0480722f36d5a266d2faaf00d
>Author: Uros Bizjak <ubizjak(a)gmail.com>
>Date: Mon Jun 16 11:52:57 2025 +0200
>
> x86/vdso: Fix output operand size of RDPID
>
> [ Upstream commit ac9c408ed19d535289ca59200dd6a44a6a2d6036 ]
>
> RDPID instruction outputs to a word-sized register (64-bit on x86_64 and
> 32-bit on x86_32). Use an unsigned long variable to store the correct size.
>
> LSL outputs to 32-bit register, use %k operand prefix to always print the
> 32-bit name of the register.
>
> Use RDPID insn mnemonic while at it as the minimum binutils version of
> 2.30 supports it.
>
> [ bp: Merge two patches touching the same function into a single one. ]
>
> Fixes: ffebbaedc861 ("x86/vdso: Introduce helper functions for CPU and node number")
> Signed-off-by: Uros Bizjak <ubizjak(a)gmail.com>
> Signed-off-by: Borislav Petkov (AMD) <bp(a)alien8.de>
> Link: https://lore.kernel.org/20250616095315.230620-1-ubizjak@gmail.com
> Signed-off-by: Sasha Levin <sashal(a)kernel.org>
>
>diff --git a/arch/x86/include/asm/segment.h b/arch/x86/include/asm/segment.h
>index 77d8f49b92bdd..f59ae7186940a 100644
>--- a/arch/x86/include/asm/segment.h
>+++ b/arch/x86/include/asm/segment.h
>@@ -244,7 +244,7 @@ static inline unsigned long vdso_encode_cpunode(int cpu, unsigned long node)
>
> static inline void vdso_read_cpunode(unsigned *cpu, unsigned *node)
> {
>- unsigned int p;
>+ unsigned long p;
>
> /*
> * Load CPU and node number from the GDT. LSL is faster than RDTSCP
>@@ -254,10 +254,10 @@ static inline void vdso_read_cpunode(unsigned *cpu, unsigned *node)
> *
> * If RDPID is available, use it.
> */
>- alternative_io ("lsl %[seg],%[p]",
>- ".byte 0xf3,0x0f,0xc7,0xf8", /* RDPID %eax/rax */
>+ alternative_io ("lsl %[seg],%k[p]",
>+ "rdpid %[p]",
> X86_FEATURE_RDPID,
>- [p] "=a" (p), [seg] "r" (__CPUNODE_SEG));
>+ [p] "=r" (p), [seg] "r" (__CPUNODE_SEG));
>
> if (cpu)
> *cpu = (p & VDSO_CPUNODE_MASK);
What the actual hell?!
Doesn't *anyone* know that x86 zero-extends a 32-bit value to 64 bits?
All this code does is put a completely unnecessary REX prefix on RDPID.
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This series fixes an issue with DMABUF support in the IIO subsystem where
the wrong DMA device could be used for buffer mapping operations. This
becomes critical on systems like Xilinx/AMD ZynqMP Ultrascale where memory
can be mapped above the 32-bit address range.
Problem:
--------
The current IIO DMABUF implementation assumes it can use the parent device
of the IIO device for DMA operations. However, this device may not have
the appropriate DMA mask configuration for accessing high memory addresses.
On systems where memory is mapped above 32-bits, this leads to the use of
bounce buffers through swiotlb, significantly impacting performance.
Solution:
---------
This series introduces a new .get_dma_dev() callback in the buffer access
functions that allows buffer implementations to specify the correct DMA
device that should be used for DMABUF operations. The DMA buffer
infrastructure implements this callback to return the device that actually
owns the DMA channel, ensuring proper memory mapping without bounce buffers.
Changes:
--------
1. Add .get_dma_dev() callback to iio_buffer_access_funcs and update core
DMABUF code to use it when available
2. Implement the callback in the DMA buffer infrastructure
3. Wire up the callback in the dmaengine buffer implementation
This ensures that DMABUF operations use the device with the correct DMA
configuration, eliminating unnecessary bounce buffer usage and improving
performance on high-memory systems.
(AI generated cover. I would not be this formal but I guess is not
that bad :))
---
Changes in v3:
- Patch 1
* Add a new iio_buffer_get_dma_dev() helper to get the DMA dev.
- Link to v2: https://lore.kernel.org/r/20251006-fix-iio-dmabuf-get-dma-device-v2-0-d960b…
---
Nuno Sá (3):
iio: buffer: support getting dma channel from the buffer
iio: buffer-dma: support getting the DMA channel
iio: buffer-dmaengine: enable .get_dma_dev()
drivers/iio/buffer/industrialio-buffer-dma.c | 6 ++++++
drivers/iio/buffer/industrialio-buffer-dmaengine.c | 2 ++
drivers/iio/industrialio-buffer.c | 21 ++++++++++++++++-----
include/linux/iio/buffer-dma.h | 1 +
include/linux/iio/buffer_impl.h | 2 ++
5 files changed, 27 insertions(+), 5 deletions(-)
---
base-commit: b9700f87939f0f477e5c00db817f54ab8a97702b
change-id: 20250930-fix-iio-dmabuf-get-dma-device-339ac70543db
--
Thanks!
- Nuno Sá
This series fixes an issue with DMABUF support in the IIO subsystem where
the wrong DMA device could be used for buffer mapping operations. This
becomes critical on systems like Xilinx/AMD ZynqMP Ultrascale where memory
can be mapped above the 32-bit address range.
Problem:
--------
The current IIO DMABUF implementation assumes it can use the parent device
of the IIO device for DMA operations. However, this device may not have
the appropriate DMA mask configuration for accessing high memory addresses.
On systems where memory is mapped above 32-bits, this leads to the use of
bounce buffers through swiotlb, significantly impacting performance.
Solution:
---------
This series introduces a new .get_dma_dev() callback in the buffer access
functions that allows buffer implementations to specify the correct DMA
device that should be used for DMABUF operations. The DMA buffer
infrastructure implements this callback to return the device that actually
owns the DMA channel, ensuring proper memory mapping without bounce buffers.
Changes:
--------
1. Add .get_dma_dev() callback to iio_buffer_access_funcs and update core
DMABUF code to use it when available
2. Implement the callback in the DMA buffer infrastructure
3. Wire up the callback in the dmaengine buffer implementation
This ensures that DMABUF operations use the device with the correct DMA
configuration, eliminating unnecessary bounce buffer usage and improving
performance on high-memory systems.
(AI generated cover. I would not be this formal but I guess is not
that bad :))
---
Changes in v2:
- Dropped Fixes tags on the first two patches and Cc stable them instead
(as prerequisites for the third patch).
- Link to v1: https://lore.kernel.org/r/20251002-fix-iio-dmabuf-get-dma-device-v1-0-c1c99…
---
Nuno Sá (3):
iio: buffer: support getting dma channel from the buffer
iio: buffer-dma: support getting the DMA channel
iio: buffer-dmaengine: enable .get_dma_dev()
drivers/iio/buffer/industrialio-buffer-dma.c | 6 +++++
drivers/iio/buffer/industrialio-buffer-dmaengine.c | 2 ++
drivers/iio/industrialio-buffer.c | 28 +++++++++++++++++-----
include/linux/iio/buffer-dma.h | 1 +
include/linux/iio/buffer_impl.h | 2 ++
5 files changed, 33 insertions(+), 6 deletions(-)
---
base-commit: b9700f87939f0f477e5c00db817f54ab8a97702b
change-id: 20250930-fix-iio-dmabuf-get-dma-device-339ac70543db
--
Thanks!
- Nuno Sá
From: Celeste Liu <uwu(a)coelacanthus.name>
The gs_usb driver supports USB devices with more than 1 CAN channel.
In old kernel before 3.15, it uses net_device->dev_id to distinguish
different channel in userspace, which was done in commit
acff76fa45b4 ("can: gs_usb: gs_make_candev(): set netdev->dev_id").
But since 3.15, the correct way is populating net_device->dev_port.
And according to documentation, if network device support multiple
interface, lack of net_device->dev_port SHALL be treated as a bug.
Fixes: acff76fa45b4 ("can: gs_usb: gs_make_candev(): set netdev->dev_id")
Cc: stable(a)vger.kernel.org
Signed-off-by: Celeste Liu <uwu(a)coelacanthus.name>
Link: https://patch.msgid.link/20250930-gs-usb-populate-net_device-dev_port-v1-1-…
Signed-off-by: Marc Kleine-Budde <mkl(a)pengutronix.de>
---
drivers/net/can/usb/gs_usb.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/drivers/net/can/usb/gs_usb.c b/drivers/net/can/usb/gs_usb.c
index 9fb4cbbd6d6d..69b8d6da651b 100644
--- a/drivers/net/can/usb/gs_usb.c
+++ b/drivers/net/can/usb/gs_usb.c
@@ -1245,6 +1245,7 @@ static struct gs_can *gs_make_candev(unsigned int channel,
netdev->flags |= IFF_ECHO; /* we support full roundtrip echo */
netdev->dev_id = channel;
+ netdev->dev_port = channel;
/* dev setup */
strcpy(dev->bt_const.name, KBUILD_MODNAME);
--
2.51.0
From: Celeste Liu <uwu(a)coelacanthus.name>
This issue was found by Runcheng Lu when develop HSCanT USB to CAN FD
converter[1]. The original developers may have only 3 interfaces
device to test so they write 3 here and wait for future change.
During the HSCanT development, we actually used 4 interfaces, so the
limitation of 3 is not enough now. But just increase one is not
future-proofed. Since the channel index type in gs_host_frame is u8,
just make canch[] become a flexible array with a u8 index, so it
naturally constraint by U8_MAX and avoid statically allocate 256
pointer for every gs_usb device.
[1]: https://github.com/cherry-embedded/HSCanT-hardware
Fixes: d08e973a77d1 ("can: gs_usb: Added support for the GS_USB CAN devices")
Reported-by: Runcheng Lu <runcheng.lu(a)hpmicro.com>
Cc: stable(a)vger.kernel.org
Reviewed-by: Vincent Mailhol <mailhol(a)kernel.org>
Signed-off-by: Celeste Liu <uwu(a)coelacanthus.name>
Link: https://patch.msgid.link/20250930-gs-usb-max-if-v5-1-863330bf6666@coelacant…
Signed-off-by: Marc Kleine-Budde <mkl(a)pengutronix.de>
---
drivers/net/can/usb/gs_usb.c | 22 ++++++++++------------
1 file changed, 10 insertions(+), 12 deletions(-)
diff --git a/drivers/net/can/usb/gs_usb.c b/drivers/net/can/usb/gs_usb.c
index c9482d6e947b..9fb4cbbd6d6d 100644
--- a/drivers/net/can/usb/gs_usb.c
+++ b/drivers/net/can/usb/gs_usb.c
@@ -289,11 +289,6 @@ struct gs_host_frame {
#define GS_MAX_RX_URBS 30
#define GS_NAPI_WEIGHT 32
-/* Maximum number of interfaces the driver supports per device.
- * Current hardware only supports 3 interfaces. The future may vary.
- */
-#define GS_MAX_INTF 3
-
struct gs_tx_context {
struct gs_can *dev;
unsigned int echo_id;
@@ -324,7 +319,6 @@ struct gs_can {
/* usb interface struct */
struct gs_usb {
- struct gs_can *canch[GS_MAX_INTF];
struct usb_anchor rx_submitted;
struct usb_device *udev;
@@ -336,9 +330,11 @@ struct gs_usb {
unsigned int hf_size_rx;
u8 active_channels;
+ u8 channel_cnt;
unsigned int pipe_in;
unsigned int pipe_out;
+ struct gs_can *canch[] __counted_by(channel_cnt);
};
/* 'allocate' a tx context.
@@ -599,7 +595,7 @@ static void gs_usb_receive_bulk_callback(struct urb *urb)
}
/* device reports out of range channel id */
- if (hf->channel >= GS_MAX_INTF)
+ if (hf->channel >= parent->channel_cnt)
goto device_detach;
dev = parent->canch[hf->channel];
@@ -699,7 +695,7 @@ static void gs_usb_receive_bulk_callback(struct urb *urb)
/* USB failure take down all interfaces */
if (rc == -ENODEV) {
device_detach:
- for (rc = 0; rc < GS_MAX_INTF; rc++) {
+ for (rc = 0; rc < parent->channel_cnt; rc++) {
if (parent->canch[rc])
netif_device_detach(parent->canch[rc]->netdev);
}
@@ -1460,17 +1456,19 @@ static int gs_usb_probe(struct usb_interface *intf,
icount = dconf.icount + 1;
dev_info(&intf->dev, "Configuring for %u interfaces\n", icount);
- if (icount > GS_MAX_INTF) {
+ if (icount > type_max(parent->channel_cnt)) {
dev_err(&intf->dev,
"Driver cannot handle more that %u CAN interfaces\n",
- GS_MAX_INTF);
+ type_max(parent->channel_cnt));
return -EINVAL;
}
- parent = kzalloc(sizeof(*parent), GFP_KERNEL);
+ parent = kzalloc(struct_size(parent, canch, icount), GFP_KERNEL);
if (!parent)
return -ENOMEM;
+ parent->channel_cnt = icount;
+
init_usb_anchor(&parent->rx_submitted);
usb_set_intfdata(intf, parent);
@@ -1531,7 +1529,7 @@ static void gs_usb_disconnect(struct usb_interface *intf)
return;
}
- for (i = 0; i < GS_MAX_INTF; i++)
+ for (i = 0; i < parent->channel_cnt; i++)
if (parent->canch[i])
gs_destroy_candev(parent->canch[i]);
base-commit: 2c95a756e0cfc19af6d0b32b0c6cf3bada334998
--
2.51.0