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 <[email protected]>
Signed-off-by: Zou Wei <[email protected]>
---
drivers/watchdog/lpc18xx_wdt.c | 2 +-
drivers/watchdog/w83877f_wdt.c | 2 +-
2 files changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/watchdog/lpc18xx_wdt.c b/drivers/watchdog/lpc18xx_wdt.c
index 78cf11c..60b6d74 100644
--- a/drivers/watchdog/lpc18xx_wdt.c
+++ b/drivers/watchdog/lpc18xx_wdt.c
@@ -292,7 +292,7 @@ static int lpc18xx_wdt_remove(struct platform_device *pdev)
struct lpc18xx_wdt_dev *lpc18xx_wdt = platform_get_drvdata(pdev);
dev_warn(&pdev->dev, "I quit now, hardware will probably reboot!\n");
- del_timer(&lpc18xx_wdt->timer);
+ del_timer_sync(&lpc18xx_wdt->timer);
return 0;
}
diff --git a/drivers/watchdog/w83877f_wdt.c b/drivers/watchdog/w83877f_wdt.c
index 5772cc5..f265086 100644
--- a/drivers/watchdog/w83877f_wdt.c
+++ b/drivers/watchdog/w83877f_wdt.c
@@ -166,7 +166,7 @@ static void wdt_startup(void)
static void wdt_turnoff(void)
{
/* Stop the timer */
- del_timer(&timer);
+ del_timer_sync(&timer);
wdt_change(WDT_DISABLE);
--
2.6.2
On Wed, May 12, 2021 at 02:57:56PM +0800, 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 <[email protected]>
> Signed-off-by: Zou Wei <[email protected]>
If you have more of those, _please_ submit them together to save review time.
Reviewed-by: Guenter Roeck <[email protected]>
Guenter
> ---
> drivers/watchdog/lpc18xx_wdt.c | 2 +-
> drivers/watchdog/w83877f_wdt.c | 2 +-
> 2 files changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/watchdog/lpc18xx_wdt.c b/drivers/watchdog/lpc18xx_wdt.c
> index 78cf11c..60b6d74 100644
> --- a/drivers/watchdog/lpc18xx_wdt.c
> +++ b/drivers/watchdog/lpc18xx_wdt.c
> @@ -292,7 +292,7 @@ static int lpc18xx_wdt_remove(struct platform_device *pdev)
> struct lpc18xx_wdt_dev *lpc18xx_wdt = platform_get_drvdata(pdev);
>
> dev_warn(&pdev->dev, "I quit now, hardware will probably reboot!\n");
> - del_timer(&lpc18xx_wdt->timer);
> + del_timer_sync(&lpc18xx_wdt->timer);
>
> return 0;
> }
> diff --git a/drivers/watchdog/w83877f_wdt.c b/drivers/watchdog/w83877f_wdt.c
> index 5772cc5..f265086 100644
> --- a/drivers/watchdog/w83877f_wdt.c
> +++ b/drivers/watchdog/w83877f_wdt.c
> @@ -166,7 +166,7 @@ static void wdt_startup(void)
> static void wdt_turnoff(void)
> {
> /* Stop the timer */
> - del_timer(&timer);
> + del_timer_sync(&timer);
>
> wdt_change(WDT_DISABLE);
>
> --
> 2.6.2
>
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 <[email protected]>
> Signed-off-by: Zou Wei <[email protected]>
Acked-by: Vladimir Zapolskiy <[email protected]>
--
Best wishes,
Vladimir
Hi Guenter,
Thanks for your review. If there are similar issues in the future, I
will collect them together and submit as one patch.
On 2021/5/12 22:06, Guenter Roeck wrote:
> On Wed, May 12, 2021 at 02:57:56PM +0800, 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 <[email protected]>
>> Signed-off-by: Zou Wei <[email protected]>
>
> If you have more of those, _please_ submit them together to save review time.
>
> Reviewed-by: Guenter Roeck <[email protected]>
>
> Guenter
> >> ---
>> drivers/watchdog/lpc18xx_wdt.c | 2 +-
>> drivers/watchdog/w83877f_wdt.c | 2 +-
>> 2 files changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/watchdog/lpc18xx_wdt.c b/drivers/watchdog/lpc18xx_wdt.c
>> index 78cf11c..60b6d74 100644
>> --- a/drivers/watchdog/lpc18xx_wdt.c
>> +++ b/drivers/watchdog/lpc18xx_wdt.c
>> @@ -292,7 +292,7 @@ static int lpc18xx_wdt_remove(struct platform_device *pdev)
>> struct lpc18xx_wdt_dev *lpc18xx_wdt = platform_get_drvdata(pdev);
>>
>> dev_warn(&pdev->dev, "I quit now, hardware will probably reboot!\n");
>> - del_timer(&lpc18xx_wdt->timer);
>> + del_timer_sync(&lpc18xx_wdt->timer);
>>
>> return 0;
>> }
>> diff --git a/drivers/watchdog/w83877f_wdt.c b/drivers/watchdog/w83877f_wdt.c
>> index 5772cc5..f265086 100644
>> --- a/drivers/watchdog/w83877f_wdt.c
>> +++ b/drivers/watchdog/w83877f_wdt.c
>> @@ -166,7 +166,7 @@ static void wdt_startup(void)
>> static void wdt_turnoff(void)
>> {
>> /* Stop the timer */
>> - del_timer(&timer);
>> + del_timer_sync(&timer);
>>
>> wdt_change(WDT_DISABLE);
>>
>> --
>> 2.6.2
>>
> .
>