linux-kernel - [PATCH AUTOSEL 4.19 06/22] watchdog: Fix possible use-after-free in wdt

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20210710235143.3222129-6-sashal@kernel.org>
Date:   Sat, 10 Jul 2021 19:51:27 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Zou Wei <zou_wei@...wei.com>, Hulk Robot <hulkci@...wei.com>,
        Guenter Roeck <linux@...ck-us.net>,
        Wim Van Sebroeck <wim@...ux-watchdog.org>,
        Sasha Levin <sashal@...nel.org>, linux-watchdog@...r.kernel.org
Subject: [PATCH AUTOSEL 4.19 06/22] watchdog: Fix possible use-after-free in wdt_startup()

From: Zou Wei <zou_wei@...wei.com>

[ Upstream commit c08a6b31e4917034f0ed0cb457c3bb209576f542 ]

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@...wei.com>
Signed-off-by: Zou Wei <zou_wei@...wei.com>
Reviewed-by: Guenter Roeck <linux@...ck-us.net>
Link: https://lore.kernel.org/r/1620716495-108352-1-git-send-email-zou_wei@huawei.com
Signed-off-by: Guenter Roeck <linux@...ck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@...ux-watchdog.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/watchdog/sbc60xxwdt.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/watchdog/sbc60xxwdt.c b/drivers/watchdog/sbc60xxwdt.c
index 87333a41f753..1702df7f8c38 100644
--- a/drivers/watchdog/sbc60xxwdt.c
+++ b/drivers/watchdog/sbc60xxwdt.c
@@ -152,7 +152,7 @@ static void wdt_startup(void)
 static void wdt_turnoff(void)
 {
 	/* Stop the timer */
-	del_timer(&timer);
+	del_timer_sync(&timer);
 	inb_p(wdt_stop);
 	pr_info("Watchdog timer is now disabled...\n");
 }
-- 
2.30.2