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

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[ Upstream commit d0212f095a ]

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>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Acked-by: Vladimir Zapolskiy <vz@mleia.com>
Link: https://lore.kernel.org/r/1620802676-19701-1-git-send-email-zou_wei@huawei.com
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Zou Wei
2021-05-12 14:57:56 +08:00
committed by Greg Kroah-Hartman
parent a173e3b62c
commit 66ba9cf929
2 changed files with 2 additions and 2 deletions
Download Patch File Download Diff File Expand all files Collapse all files

2
drivers/watchdog/lpc18xx_wdt.c
View File

@@ -292,7 +292,7 @@ static int lpc18xx_wdt_remove(struct platform_device *pdev)
struct lpc18xx_wdt_dev *lpc18xx_wdt = platform_get_drvdata(pdev); struct lpc18xx_wdt_dev *lpc18xx_wdt = platform_get_drvdata(pdev);
dev_warn(&pdev->dev, "I quit now, hardware will probably reboot!\n"); 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; return 0;
} }

2
drivers/watchdog/w83877f_wdt.c
View File

@@ -166,7 +166,7 @@ static void wdt_startup(void)
static void wdt_turnoff(void) static void wdt_turnoff(void)
{ {
/* Stop the timer */ /* Stop the timer */
del_timer(&timer); del_timer_sync(&timer);
wdt_change(WDT_DISABLE); wdt_change(WDT_DISABLE);