From: Kees Cook <keescook(a)chromium.org>
Subject: lib/bug.c: exclude non-BUG/WARN exceptions from report_bug()
b8347c219649 ("x86/debug: Handle warnings before the notifier chain, to
fix KGDB crash") changed the ordering of fixups, and did not take into
account the case of x86 processing non-WARN() and non-BUG() exceptions.
This would lead to output of a false BUG line with no other information.
In the case of a refcount exception, it would be immediately followed by
the refcount WARN(), producing very strange double-"cut here":
lkdtm: attempting bad refcount_inc() overflow
------------[ cut here ]------------
Kernel BUG at 0000000065f29de5 [verbose debug info unavailable]
------------[ cut here ]------------
refcount_t overflow at lkdtm_REFCOUNT_INC_OVERFLOW+0x6b/0x90 in cat[3065], uid/euid: 0/0
WARNING: CPU: 0 PID: 3065 at kernel/panic.c:657 refcount_error_report+0x9a/0xa4
...
In the prior ordering, exceptions were searched first:
do_trap_no_signal(struct task_struct *tsk, int trapnr, char *str,
...
if (fixup_exception(regs, trapnr))
return 0;
- if (fixup_bug(regs, trapnr))
- return 0;
-
As a result, fixup_bugs()'s is_valid_bugaddr() didn't take into account
needing to search the exception list first, since that had already
happened.
So, instead of searching the exception list twice (once in
is_valid_bugaddr() and then again in fixup_exception()), just add a simple
sanity check to report_bug() that will immediately bail out if a BUG() (or
WARN()) entry is not found.
Link: http://lkml.kernel.org/r/20180301225934.GA34350@beast
Fixes: b8347c219649 ("x86/debug: Handle warnings before the notifier chain, to fix KGDB crash")
Signed-off-by: Kees Cook <keescook(a)chromium.org>
Cc: Ingo Molnar <mingo(a)kernel.org>
Cc: Thomas Gleixner <tglx(a)linutronix.de>
Cc: Peter Zijlstra <peterz(a)infradead.org>
Cc: Borislav Petkov <bp(a)alien8.de>
Cc: Richard Weinberger <richard.weinberger(a)gmail.com>
Cc: <stable(a)vger.kernel.org>
Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org>
---
lib/bug.c | 2 ++
1 file changed, 2 insertions(+)
diff -puN lib/bug.c~bug-exclude-non-bug-warn-exceptions-from-report_bug lib/bug.c
--- a/lib/bug.c~bug-exclude-non-bug-warn-exceptions-from-report_bug
+++ a/lib/bug.c
@@ -150,6 +150,8 @@ enum bug_trap_type report_bug(unsigned l
return BUG_TRAP_TYPE_NONE;
bug = find_bug(bugaddr);
+ if (!bug)
+ return BUG_TRAP_TYPE_NONE;
file = NULL;
line = 0;
_
This is a note to let you know that I've just added the patch titled
dm io: fix duplicate bio completion due to missing ref count
to the 4.4-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:
dm-io-fix-duplicate-bio-completion-due-to-missing-ref-count.patch
and it can be found in the queue-4.4 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.
>From feb7695fe9fb83084aa29de0094774f4c9d4c9fc Mon Sep 17 00:00:00 2001
From: Mike Snitzer <snitzer(a)redhat.com>
Date: Tue, 20 Jun 2017 19:14:30 -0400
Subject: dm io: fix duplicate bio completion due to missing ref count
From: Mike Snitzer <snitzer(a)redhat.com>
commit feb7695fe9fb83084aa29de0094774f4c9d4c9fc upstream.
If only a subset of the devices associated with multiple regions support
a given special operation (eg. DISCARD) then the dec_count() that is
used to set error for the region must increment the io->count.
Otherwise, when the dec_count() is called it can cause the dm-io
caller's bio to be completed multiple times. As was reported against
the dm-mirror target that had mirror legs with a mix of discard
capabilities.
Bug: https://bugzilla.kernel.org/show_bug.cgi?id=196077
Reported-by: Zhang Yi <yizhan(a)redhat.com>
Signed-off-by: Mike Snitzer <snitzer(a)redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh(a)linuxfoundation.org>
---
drivers/md/dm-io.c | 1 +
1 file changed, 1 insertion(+)
--- a/drivers/md/dm-io.c
+++ b/drivers/md/dm-io.c
@@ -300,6 +300,7 @@ static void do_region(int rw, unsigned r
else if (rw & REQ_WRITE_SAME)
special_cmd_max_sectors = q->limits.max_write_same_sectors;
if ((rw & (REQ_DISCARD | REQ_WRITE_SAME)) && special_cmd_max_sectors == 0) {
+ atomic_inc(&io->count);
dec_count(io, region, -EOPNOTSUPP);
return;
}
Patches currently in stable-queue which might be from snitzer(a)redhat.com are
queue-4.4/dm-io-fix-duplicate-bio-completion-due-to-missing-ref-count.patch
This is a note to let you know that I've just added the patch titled
dm io: fix duplicate bio completion due to missing ref count
to the 3.18-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:
dm-io-fix-duplicate-bio-completion-due-to-missing-ref-count.patch
and it can be found in the queue-3.18 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.
>From feb7695fe9fb83084aa29de0094774f4c9d4c9fc Mon Sep 17 00:00:00 2001
From: Mike Snitzer <snitzer(a)redhat.com>
Date: Tue, 20 Jun 2017 19:14:30 -0400
Subject: dm io: fix duplicate bio completion due to missing ref count
From: Mike Snitzer <snitzer(a)redhat.com>
commit feb7695fe9fb83084aa29de0094774f4c9d4c9fc upstream.
If only a subset of the devices associated with multiple regions support
a given special operation (eg. DISCARD) then the dec_count() that is
used to set error for the region must increment the io->count.
Otherwise, when the dec_count() is called it can cause the dm-io
caller's bio to be completed multiple times. As was reported against
the dm-mirror target that had mirror legs with a mix of discard
capabilities.
Bug: https://bugzilla.kernel.org/show_bug.cgi?id=196077
Reported-by: Zhang Yi <yizhan(a)redhat.com>
Signed-off-by: Mike Snitzer <snitzer(a)redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh(a)linuxfoundation.org>
---
drivers/md/dm-io.c | 1 +
1 file changed, 1 insertion(+)
--- a/drivers/md/dm-io.c
+++ b/drivers/md/dm-io.c
@@ -299,6 +299,7 @@ static void do_region(int rw, unsigned r
else if (rw & REQ_WRITE_SAME)
special_cmd_max_sectors = q->limits.max_write_same_sectors;
if ((rw & (REQ_DISCARD | REQ_WRITE_SAME)) && special_cmd_max_sectors == 0) {
+ atomic_inc(&io->count);
dec_count(io, region, -EOPNOTSUPP);
return;
}
Patches currently in stable-queue which might be from snitzer(a)redhat.com are
queue-3.18/dm-io-fix-duplicate-bio-completion-due-to-missing-ref-count.patch
Hi
This is backport of the upstream commit that fixes memory corruption in
dm-io. It is suitable for stable kernels 3.18 to 4.7. (the bug didn't
exist before 3.18)
Mikulas
commit feb7695fe9fb83084aa29de0094774f4c9d4c9fc
Author: Mike Snitzer <snitzer(a)redhat.com>
Date: Tue Jun 20 19:14:30 2017 -0400
dm io: fix duplicate bio completion due to missing ref count
If only a subset of the devices associated with multiple regions support
a given special operation (eg. DISCARD) then the dec_count() that is
used to set error for the region must increment the io->count.
Otherwise, when the dec_count() is called it can cause the dm-io
caller's bio to be completed multiple times. As was reported against
the dm-mirror target that had mirror legs with a mix of discard
capabilities.
Bug: https://bugzilla.kernel.org/show_bug.cgi?id=196077
Reported-by: Zhang Yi <yizhan(a)redhat.com>
Signed-off-by: Mike Snitzer <snitzer(a)redhat.com>
---
drivers/md/dm-io.c | 1 +
1 file changed, 1 insertion(+)
Index: linux-stable/drivers/md/dm-io.c
===================================================================
--- linux-stable.orig/drivers/md/dm-io.c 2018-03-06 14:13:59.000000000 +0100
+++ linux-stable/drivers/md/dm-io.c 2018-03-06 14:14:23.000000000 +0100
@@ -316,6 +316,7 @@ static void do_region(int op, int op_fla
special_cmd_max_sectors = q->limits.max_write_same_sectors;
if ((op == REQ_OP_DISCARD || op == REQ_OP_WRITE_SAME) &&
special_cmd_max_sectors == 0) {
+ atomic_inc(&io->count);
dec_count(io, region, -EOPNOTSUPP);
return;
}
If there is a pending work, we just need to add the new dr into
the dr_list.
This is suggested by Michael Kelley.
Signed-off-by: Dexuan Cui <decui(a)microsoft.com>
Cc: Vitaly Kuznetsov <vkuznets(a)redhat.com>
Cc: Jack Morgenstein <jackm(a)mellanox.com>
Cc: stable(a)vger.kernel.org
Cc: Stephen Hemminger <sthemmin(a)microsoft.com>
Cc: K. Y. Srinivasan <kys(a)microsoft.com>
Cc: Michael Kelley (EOSG) <Michael.H.Kelley(a)microsoft.com>
---
drivers/pci/host/pci-hyperv.c | 15 +++++++++++++--
1 file changed, 13 insertions(+), 2 deletions(-)
diff --git a/drivers/pci/host/pci-hyperv.c b/drivers/pci/host/pci-hyperv.c
index 3a385212f666..265ba11e53e2 100644
--- a/drivers/pci/host/pci-hyperv.c
+++ b/drivers/pci/host/pci-hyperv.c
@@ -1733,6 +1733,7 @@ static void hv_pci_devices_present(struct hv_pcibus_device *hbus,
struct hv_dr_state *dr;
struct hv_dr_work *dr_wrk;
unsigned long flags;
+ bool pending_dr;
dr_wrk = kzalloc(sizeof(*dr_wrk), GFP_NOWAIT);
if (!dr_wrk)
@@ -1756,11 +1757,21 @@ static void hv_pci_devices_present(struct hv_pcibus_device *hbus,
}
spin_lock_irqsave(&hbus->device_list_lock, flags);
+ /*
+ * If pending_dr is true, we have already queued a work,
+ * which will see the new dr. Otherwise, we need to
+ * queue a new work.
+ */
+ pending_dr = !list_empty(&hbus->dr_list);
list_add_tail(&dr->list_entry, &hbus->dr_list);
spin_unlock_irqrestore(&hbus->device_list_lock, flags);
- get_hvpcibus(hbus);
- queue_work(hbus->wq, &dr_wrk->wrk);
+ if (pending_dr) {
+ kfree(dr_wrk);
+ } else {
+ get_hvpcibus(hbus);
+ queue_work(hbus->wq, &dr_wrk->wrk);
+ }
}
/**
--
2.7.4