A recent change fixing a device reference leak in a UDC driver
introduced a potential use-after-free in the non-OF case as the
isp1301_get_client() helper only increases the reference count for the
returned I2C device in the OF case.
Increment the reference count also for non-OF so that the caller can
decrement it unconditionally.
Note that this is inherently racy just as using the returned I2C device
is since nothing is preventing the PHY driver from being unbound while
in use.
Fixes: c84117912bdd ("USB: lpc32xx_udc: Fix error handling in probe")
Cc: stable(a)vger.kernel.org
Cc: Ma Ke <make24(a)iscas.ac.cn>
Signed-off-by: Johan Hovold <johan(a)kernel.org>
---
drivers/usb/phy/phy-isp1301.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/drivers/usb/phy/phy-isp1301.c b/drivers/usb/phy/phy-isp1301.c
index f9b5c411aee4..2940f0c84e1b 100644
--- a/drivers/usb/phy/phy-isp1301.c
+++ b/drivers/usb/phy/phy-isp1301.c
@@ -149,7 +149,12 @@ struct i2c_client *isp1301_get_client(struct device_node *node)
return client;
/* non-DT: only one ISP1301 chip supported */
- return isp1301_i2c_client;
+ if (isp1301_i2c_client) {
+ get_device(&isp1301_i2c_client->dev);
+ return isp1301_i2c_client;
+ }
+
+ return NULL;
}
EXPORT_SYMBOL_GPL(isp1301_get_client);
--
2.51.2
Hi ,
I hope my previous email reached you and you've had the chance to read it.
Let me know if you need more specifics on the numbers and associated expenses.
Regards
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Marketing Manager
Campaign Data Leads.,
Please reply with REMOVE if you don't wish to receive further emails
-----Original Message-----
From: Jessica Garcia
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Jessica
Marketing Manager
Campaign Data Leads.,
Please reply with REMOVE if you don't wish to receive further emails
The Task::group_leader() method currently allows you to access the
group_leader() of any task, for example one you hold a refcount to. But
this is not safe in general since the group leader could change when a
task exits. See for example commit a15f37a40145c ("kernel/sys.c: fix the
racy usage of task_lock(tsk->group_leader) in sys_prlimit64() paths").
All existing users of Task::group_leader() call this method on current,
which is guaranteed running, so there's not an actual issue in Rust code
today. But to prevent code in the future from making this mistake,
restrict Task::group_leader() so that it can only be called on current.
There are some other cases where accessing task->group_leader is okay.
For example it can be safe if you hold tasklist_lock or rcu_read_lock().
However, only supporting current->group_leader is sufficient for all
in-tree Rust users of group_leader right now. Safe Rust functionality
for accessing it under rcu or while holding tasklist_lock may be added
in the future if required by any future Rust module.
Reported-by: Oleg Nesterov <oleg(a)redhat.com>
Closes: https://lore.kernel.org/all/aTLnV-5jlgfk1aRK@redhat.com/
Fixes: 313c4281bc9d ("rust: add basic `Task`")
Cc: stable(a)vger.kernel.org
Signed-off-by: Alice Ryhl <aliceryhl(a)google.com>
---
The rust/kernel/task.rs file has had changes land through a few
different trees:
* Originally task.rs landed through Christian's tree together with
file.rs and pid_namespace.rs
* The change to add CurrentTask landed through Andrew Morton's tree
together with mm.rs
* There was a patch to mark some methods #[inline] that landed through
tip via Boqun.
I don't think there's a clear owner for this file, so to break ambiguity
I'm doing to declare that this patch is intended for Andrew Morton's
tree. Please let me know if you think a different tree is appropriate.
---
rust/kernel/task.rs | 24 ++++++++++++------------
1 file changed, 12 insertions(+), 12 deletions(-)
diff --git a/rust/kernel/task.rs b/rust/kernel/task.rs
index 49fad6de06740a9b9ad80b2f4b430cc28cd134fa..9440692a3a6d0d3f908d61d51dcd377a272f6957 100644
--- a/rust/kernel/task.rs
+++ b/rust/kernel/task.rs
@@ -204,18 +204,6 @@ pub fn as_ptr(&self) -> *mut bindings::task_struct {
self.0.get()
}
- /// Returns the group leader of the given task.
- pub fn group_leader(&self) -> &Task {
- // SAFETY: The group leader of a task never changes after initialization, so reading this
- // field is not a data race.
- let ptr = unsafe { *ptr::addr_of!((*self.as_ptr()).group_leader) };
-
- // SAFETY: The lifetime of the returned task reference is tied to the lifetime of `self`,
- // and given that a task has a reference to its group leader, we know it must be valid for
- // the lifetime of the returned task reference.
- unsafe { &*ptr.cast() }
- }
-
/// Returns the PID of the given task.
pub fn pid(&self) -> Pid {
// SAFETY: The pid of a task never changes after initialization, so reading this field is
@@ -345,6 +333,18 @@ pub fn active_pid_ns(&self) -> Option<&PidNamespace> {
// `release_task()` call.
Some(unsafe { PidNamespace::from_ptr(active_ns) })
}
+
+ /// Returns the group leader of the current task.
+ pub fn group_leader(&self) -> &Task {
+ // SAFETY: The group leader of a task never changes while the task is running, and `self`
+ // is the current task, which is guaranteed running.
+ let ptr = unsafe { (*self.as_ptr()).group_leader };
+
+ // SAFETY: `current.group_leader` stays valid for at least the duration in which `current`
+ // is running, and the signature of this function ensures that the returned `&Task` can
+ // only be used while `current` is still valid, thus still running.
+ unsafe { &*ptr.cast() }
+ }
}
// SAFETY: The type invariants guarantee that `Task` is always refcounted.
---
base-commit: 8f0b4cce4481fb22653697cced8d0d04027cb1e8
change-id: 20251218-task-group-leader-a71931ced643
Best regards,
--
Alice Ryhl <aliceryhl(a)google.com>