From 8bec568d7518b1504a602ed5376bb322e4dbb270 Mon Sep 17 00:00:00 2001
From: Zou Wei <zou_wei@huawei.com>
Date: Wed, 12 May 2021 14:57:56 +0800
Subject: [PATCH] watchdog: Fix possible use-after-free by calling
del_timer_sync()
[ Upstream commit d0212f095ab56672f6f36aabc605bda205e1e0bf ]
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>
---
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 3b8bb59adf027..e9deeda1fdbf4 100644
--- a/drivers/watchdog/lpc18xx_wdt.c
+++ b/drivers/watchdog/lpc18xx_wdt.c
@@ -300,7 +300,7 @@ 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);
diff --git a/drivers/watchdog/w83877f_wdt.c b/drivers/watchdog/w83877f_wdt.c
index f0483c75ed324..4b52cf321747e 100644
--- a/drivers/watchdog/w83877f_wdt.c
+++ b/drivers/watchdog/w83877f_wdt.c
@@ -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);