This is a note to let you know that I've just added the patch titled
atm: nicstar: Fix possible use-after-free in nicstar_cleanup()
to the 5.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
atm-nicstar-fix-possible-use-after-free-in-nicstar_c.patch
and it can be found in the queue-5.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 771bb52155a684460aec3e2ccc5442d7e534c417
Author: Zou Wei <zou_wei@xxxxxxxxxx>
Date: Wed May 12 15:00:24 2021 +0800
atm: nicstar: Fix possible use-after-free in nicstar_cleanup()
[ Upstream commit 34e7434ba4e97f4b85c1423a59b2922ba7dff2ea ]
This module's remove path calls del_timer(). However, that function
does not wait until the timer handler finishes. This means that the
timer handler may still be running after the driver's remove function
has finished, which would result in a use-after-free.
Fix by calling del_timer_sync(), which makes sure the timer handler
has finished, and unable to re-schedule itself.
Reported-by: Hulk Robot <hulkci@xxxxxxxxxx>
Signed-off-by: Zou Wei <zou_wei@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/atm/nicstar.c b/drivers/atm/nicstar.c
index bb9835c62641..5ec7b6a60145 100644
--- a/drivers/atm/nicstar.c
+++ b/drivers/atm/nicstar.c
@@ -297,7 +297,7 @@ static void __exit nicstar_cleanup(void)
{
XPRINTK("nicstar: nicstar_cleanup() called.\n");
- del_timer(&ns_timer);
+ del_timer_sync(&ns_timer);
pci_unregister_driver(&nicstar_driver);
