Commit decef165 authored by Zou Wei's avatar Zou Wei Committed by Jialin Zhang
Browse files

watchdog: Fix possible use-after-free by calling del_timer_sync() 

stable inclusion
from stable-v4.19.198
commit ecd620e0fb1ff7f78fdb593379b2e6938c99707a
category: bugfix
bugzilla: https://gitee.com/src-openeuler/kernel/issues/I9RL1P
CVE: CVE-2021-47321

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=ecd620e0fb1ff7f78fdb593379b2e6938c99707a



--------------------------------

[ Upstream commit d0212f09 ]

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: default avatarHulk Robot <hulkci@huawei.com>
Signed-off-by: default avatarZou Wei <zou_wei@huawei.com>
Reviewed-by: default avatarGuenter Roeck <linux@roeck-us.net>
Acked-by: default avatarVladimir Zapolskiy <vz@mleia.com>
Link: https://lore.kernel.org/r/1620802676-19701-1-git-send-email-zou_wei@huawei.com


Signed-off-by: default avatarGuenter Roeck <linux@roeck-us.net>
Signed-off-by: default avatarWim Van Sebroeck <wim@linux-watchdog.org>
Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
Signed-off-by: default avatarJialin Zhang <zhangjialin11@huawei.com>
parent 606e9f58

drivers/watchdog/lpc18xx_wdt.c

+1 −1
Original line number Diff line number Diff line
@@ -301,7 +301,7 @@ 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);



	watchdog_unregister_device(&lpc18xx_wdt->wdt_dev);

	clk_disable_unprepare(lpc18xx_wdt->wdt_clk);

drivers/watchdog/w83877f_wdt.c

+1 −1
Original line number Diff line number Diff line
@@ -170,7 +170,7 @@ static void wdt_startup(void) 
static void wdt_turnoff(void)

{

	/* Stop the timer */

	del_timer(&timer);

	del_timer_sync(&timer);



	wdt_change(WDT_DISABLE);