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From: Sasha Levin <sashal@kernel.org>
To: linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc: Zou Wei <zou_wei@huawei.com>, Hulk Robot <hulkci@huawei.com>,
	Guenter Roeck <linux@roeck-us.net>,
	Wim Van Sebroeck <wim@linux-watchdog.org>,
	Sasha Levin <sashal@kernel.org>,
	linux-watchdog@vger.kernel.org
Subject: [PATCH AUTOSEL 4.14 07/21] watchdog: sc520_wdt: Fix possible use-after-free in wdt_turnoff()
Date: Sat, 10 Jul 2021 19:51:58 -0400	[thread overview]
Message-ID: <20210710235212.3222375-7-sashal@kernel.org> (raw)
In-Reply-To: <20210710235212.3222375-1-sashal@kernel.org>

From: Zou Wei <zou_wei@huawei.com>

[ Upstream commit 90b7c141132244e8e49a34a4c1e445cce33e07f4 ]

This module'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>
Link: https://lore.kernel.org/r/1620716691-108460-1-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/sc520_wdt.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/watchdog/sc520_wdt.c b/drivers/watchdog/sc520_wdt.c
index 1cfd3f6a13d5..08500db8324f 100644
--- a/drivers/watchdog/sc520_wdt.c
+++ b/drivers/watchdog/sc520_wdt.c
@@ -190,7 +190,7 @@ static int wdt_startup(void)
 static int wdt_turnoff(void)
 {
 	/* Stop the timer */
-	del_timer(&timer);
+	del_timer_sync(&timer);
 
 	/* Stop the watchdog */
 	wdt_config(0);
-- 
2.30.2


  parent reply	other threads:[~2021-07-10 23:55 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20210710235212.3222375-1-sashal@kernel.org>
2021-07-10 23:51 ` [PATCH AUTOSEL 4.14 06/21] watchdog: Fix possible use-after-free in wdt_startup() Sasha Levin
2021-07-10 23:51 ` Sasha Levin [this message]
2021-07-10 23:51 ` [PATCH AUTOSEL 4.14 08/21] watchdog: Fix possible use-after-free by calling del_timer_sync() Sasha Levin
2021-07-10 23:52 ` [PATCH AUTOSEL 4.14 09/21] watchdog: iTCO_wdt: Account for rebooting on second timeout Sasha Levin

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