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From: Zou Wei <zou_wei@huawei.com>
To: <wim@linux-watchdog.org>, <linux@roeck-us.net>, <vz@mleia.com>
Cc: <linux-watchdog@vger.kernel.org>,
	<linux-arm-kernel@lists.infradead.org>,
	<linux-kernel@vger.kernel.org>, Zou Wei <zou_wei@huawei.com>
Subject: [PATCH -next] watchdog: Fix possible use-after-free by calling del_timer_sync()
Date: Wed, 12 May 2021 14:57:56 +0800	[thread overview]
Message-ID: <1620802676-19701-1-git-send-email-zou_wei@huawei.com> (raw)

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>
---
 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 78cf11c..60b6d74 100644
--- a/drivers/watchdog/lpc18xx_wdt.c
+++ b/drivers/watchdog/lpc18xx_wdt.c
@@ -292,7 +292,7 @@ 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);
 
 	return 0;
 }
diff --git a/drivers/watchdog/w83877f_wdt.c b/drivers/watchdog/w83877f_wdt.c
index 5772cc5..f265086 100644
--- a/drivers/watchdog/w83877f_wdt.c
+++ b/drivers/watchdog/w83877f_wdt.c
@@ -166,7 +166,7 @@ static void wdt_startup(void)
 static void wdt_turnoff(void)
 {
 	/* Stop the timer */
-	del_timer(&timer);
+	del_timer_sync(&timer);
 
 	wdt_change(WDT_DISABLE);
 
-- 
2.6.2


WARNING: multiple messages have this Message-ID (diff)
From: Zou Wei <zou_wei@huawei.com>
To: <wim@linux-watchdog.org>, <linux@roeck-us.net>, <vz@mleia.com>
Cc: <linux-watchdog@vger.kernel.org>,
	<linux-arm-kernel@lists.infradead.org>,
	 <linux-kernel@vger.kernel.org>, Zou Wei <zou_wei@huawei.com>
Subject: [PATCH -next] watchdog: Fix possible use-after-free by calling del_timer_sync()
Date: Wed, 12 May 2021 14:57:56 +0800	[thread overview]
Message-ID: <1620802676-19701-1-git-send-email-zou_wei@huawei.com> (raw)

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>
---
 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 78cf11c..60b6d74 100644
--- a/drivers/watchdog/lpc18xx_wdt.c
+++ b/drivers/watchdog/lpc18xx_wdt.c
@@ -292,7 +292,7 @@ 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);
 
 	return 0;
 }
diff --git a/drivers/watchdog/w83877f_wdt.c b/drivers/watchdog/w83877f_wdt.c
index 5772cc5..f265086 100644
--- a/drivers/watchdog/w83877f_wdt.c
+++ b/drivers/watchdog/w83877f_wdt.c
@@ -166,7 +166,7 @@ static void wdt_startup(void)
 static void wdt_turnoff(void)
 {
 	/* Stop the timer */
-	del_timer(&timer);
+	del_timer_sync(&timer);
 
 	wdt_change(WDT_DISABLE);
 
-- 
2.6.2


_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

             reply	other threads:[~2021-05-12  6:41 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-05-12  6:57 Zou Wei [this message]
2021-05-12  6:57 ` [PATCH -next] watchdog: Fix possible use-after-free by calling del_timer_sync() Zou Wei
2021-05-12 14:06 ` Guenter Roeck
2021-05-12 14:06   ` Guenter Roeck
2021-05-13  2:01   ` Samuel Zou
2021-05-13  2:01     ` Samuel Zou
2021-05-12 17:04 ` Vladimir Zapolskiy
2021-05-12 17:04   ` Vladimir Zapolskiy

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