linux-kernel - [PATCH v2] w1: do not unlock unheld list_mutex in __w1_remove_master

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Message-Id: <1399411564-16172-1-git-send-email-khoroshilov@ispras.ru>
Date:	Wed,  7 May 2014 01:26:04 +0400
From:	Alexey Khoroshilov <khoroshilov@...ras.ru>
To:	David Fries <David@...es.net>
Cc:	Alexey Khoroshilov <khoroshilov@...ras.ru>,
	Evgeniy Polyakov <zbr@...emap.net>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	linux-kernel@...r.kernel.org, ldv-project@...uxtesting.org
Subject: [PATCH v2] w1: do not unlock unheld list_mutex in __w1_remove_master_device()

w1_process_callbacks() expects to be called with dev->list_mutex held,
but it is the fact only in w1_process(). __w1_remove_master_device()
calls w1_process_callbacks() after it releases list_mutex.

The patch fixes __w1_remove_master_device() to acquire list_mutex
for w1_process_callbacks().

Found by Linux Driver Verification project (linuxtesting.org).

Signed-off-by: Alexey Khoroshilov <khoroshilov@...ras.ru>
---
 drivers/w1/w1.c     | 2 ++
 drivers/w1/w1_int.c | 4 ++++
 2 files changed, 6 insertions(+)

diff --git a/drivers/w1/w1.c b/drivers/w1/w1.c
index ff52618cafbe..5d7341520544 100644
--- a/drivers/w1/w1.c
+++ b/drivers/w1/w1.c
@@ -1078,6 +1078,8 @@ static void w1_search_process(struct w1_master *dev, u8 search_type)
  * w1_process_callbacks() - execute each dev->async_list callback entry
  * @dev: w1_master device
  *
+ * The w1 master list_mutex must be held.
+ *
  * Return: 1 if there were commands to executed 0 otherwise
  */
 int w1_process_callbacks(struct w1_master *dev)
diff --git a/drivers/w1/w1_int.c b/drivers/w1/w1_int.c
index 9b084db739c7..728039d2efe1 100644
--- a/drivers/w1/w1_int.c
+++ b/drivers/w1/w1_int.c
@@ -219,9 +219,13 @@ void __w1_remove_master_device(struct w1_master *dev)
 
 		if (msleep_interruptible(1000))
 			flush_signals(current);
+		mutex_lock(&dev->list_mutex);
 		w1_process_callbacks(dev);
+		mutex_unlock(&dev->list_mutex);
 	}
+	mutex_lock(&dev->list_mutex);
 	w1_process_callbacks(dev);
+	mutex_unlock(&dev->list_mutex);
 
 	memset(&msg, 0, sizeof(msg));
 	msg.id.mst.id = dev->id;
-- 
1.8.3.2

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