This is a note to let you know that I've just added the patch titled
watchdog: Fix possible use-after-free in wdt_startup()
to the 4.19-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:
watchdog-fix-possible-use-after-free-in-wdt_startup.patch
and it can be found in the queue-4.19 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 448785f5699d3e229e105397dc72acacba9d39df
Author: Zou Wei <zou_wei@xxxxxxxxxx>
Date: Tue May 11 15:01:35 2021 +0800
watchdog: Fix possible use-after-free in wdt_startup()
[ Upstream commit c08a6b31e4917034f0ed0cb457c3bb209576f542 ]
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>
Reviewed-by: Guenter Roeck <linux@xxxxxxxxxxxx>
Link: https://lore.kernel.org/r/1620716495-108352-1-git-send-email-zou_wei@xxxxxxxxxx
Signed-off-by: Guenter Roeck <linux@xxxxxxxxxxxx>
Signed-off-by: Wim Van Sebroeck <wim@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/watchdog/sbc60xxwdt.c b/drivers/watchdog/sbc60xxwdt.c
index 87333a41f753..1702df7f8c38 100644
--- a/drivers/watchdog/sbc60xxwdt.c
+++ b/drivers/watchdog/sbc60xxwdt.c
@@ -152,7 +152,7 @@ static void wdt_startup(void)
static void wdt_turnoff(void)
{
/* Stop the timer */
- del_timer(&timer);
+ del_timer_sync(&timer);
inb_p(wdt_stop);
pr_info("Watchdog timer is now disabled...\n");
}
