[PATCH -next] watchdog: Fix possible use-after-free by calling del_timer_sync()

[Vladimir Zapolskiy]

On 5/12/21 9:57 AM, Zou Wei wrote:
> This driver'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 at huawei.com>
> Signed-off-by: Zou Wei <zou_wei at huawei.com>

Acked-by: Vladimir Zapolskiy <vz at mleia.com>

--
Best wishes,
Vladimir