* [PATCH -next] watchdog: Fix possible use-after-free in wdt_startup()
@ 2021-05-11 7:01 Zou Wei
2021-05-11 13:36 ` Guenter Roeck
0 siblings, 1 reply; 2+ messages in thread
From: Zou Wei @ 2021-05-11 7:01 UTC (permalink / raw)
To: wim, linux; +Cc: linux-watchdog, linux-kernel, Zou Wei
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(-)
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");
}
--
2.6.2
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH -next] watchdog: Fix possible use-after-free in wdt_startup()
2021-05-11 7:01 [PATCH -next] watchdog: Fix possible use-after-free in wdt_startup() Zou Wei
@ 2021-05-11 13:36 ` Guenter Roeck
0 siblings, 0 replies; 2+ messages in thread
From: Guenter Roeck @ 2021-05-11 13:36 UTC (permalink / raw)
To: Zou Wei, wim; +Cc: linux-watchdog, linux-kernel
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");
> }
>
^ permalink raw reply [flat|nested] 2+ messages in thread
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2021-05-11 7:01 [PATCH -next] watchdog: Fix possible use-after-free in wdt_startup() Zou Wei
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