| Message ID | 1620716495-108352-1-git-send-email-zou_wei@huawei.com (mailing list archive) |
|---|---|
| State | Accepted |
| Headers | show |
| Series | [-next] watchdog: Fix possible use-after-free in wdt_startup() | expand |
On 5/11/21 12:01 AM, Zou Wei wrote: > 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@huawei.com> > Signed-off-by: Zou Wei <zou_wei@huawei.com> Reviewed-by: Guenter Roeck <linux@roeck-us.net> > --- > drivers/watchdog/sbc60xxwdt.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/watchdog/sbc60xxwdt.c b/drivers/watchdog/sbc60xxwdt.c > index a947a63..7b97480 100644 > --- a/drivers/watchdog/sbc60xxwdt.c > +++ b/drivers/watchdog/sbc60xxwdt.c > @@ -146,7 +146,7 @@ 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"); > } >
diff --git a/drivers/watchdog/sbc60xxwdt.c b/drivers/watchdog/sbc60xxwdt.c index a947a63..7b97480 100644 --- a/drivers/watchdog/sbc60xxwdt.c +++ b/drivers/watchdog/sbc60xxwdt.c @@ -146,7 +146,7 @@ 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"); }
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@huawei.com> Signed-off-by: Zou Wei <zou_wei@huawei.com> --- drivers/watchdog/sbc60xxwdt.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)