| Message ID | 1620802676-19701-1-git-send-email-zou_wei@huawei.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [-next] watchdog: Fix possible use-after-free by calling del_timer_sync() | expand |
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 <hulkci@huawei.com> > Signed-off-by: Zou Wei <zou_wei@huawei.com> If you have more of those, _please_ submit them together to save review time. Reviewed-by: Guenter Roeck <linux@roeck-us.net> 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 <hulkci@huawei.com> > Signed-off-by: Zou Wei <zou_wei@huawei.com> Acked-by: Vladimir Zapolskiy <vz@mleia.com> -- 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 <hulkci@huawei.com> >> Signed-off-by: Zou Wei <zou_wei@huawei.com> > > If you have more of those, _please_ submit them together to save review time. > > Reviewed-by: Guenter Roeck <linux@roeck-us.net> > > 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 >> > . >
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);
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@huawei.com> Signed-off-by: Zou Wei <zou_wei@huawei.com> --- drivers/watchdog/lpc18xx_wdt.c | 2 +- drivers/watchdog/w83877f_wdt.c | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-)