linux-kernel - [PATCH] staging/easycap: fix mismatch in easycap

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Message-Id: <1314640017-27561-1-git-send-email-khoroshilov@ispras.ru>
Date:	Mon, 29 Aug 2011 21:46:57 +0400
From:	Alexey Khoroshilov <khoroshilov@...ras.ru>
To:	Greg Kroah-Hartman <gregkh@...e.de>
Cc:	Alexey Khoroshilov <khoroshilov@...ras.ru>,
	Tomas Winkler <tomas.winkler@...el.com>,
	Mike Thomas <rmthomas@...olus.org>, devel@...verdev.osuosl.org,
	linux-kernel@...r.kernel.org, ldv-project@...ras.ru
Subject: [PATCH] staging/easycap: fix mismatch in easycap_poll() mutex lock-unlock

In case if condition (kd != isdongle(peasycap)) becomes true,
easycap_poll() returns without releasing easycapdc60_dongle[kd].mutex_video.
The patch adds mutex_unlock() before that return.

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

Signed-off-by: Alexey Khoroshilov <khoroshilov@...ras.ru>
---
 drivers/staging/easycap/easycap_main.c |    4 +++-
 1 files changed, 3 insertions(+), 1 deletions(-)

diff --git a/drivers/staging/easycap/easycap_main.c b/drivers/staging/easycap/easycap_main.c
index bea2816..3ea51c3 100644
--- a/drivers/staging/easycap/easycap_main.c
+++ b/drivers/staging/easycap/easycap_main.c
@@ -953,8 +953,10 @@ static unsigned int easycap_poll(struct file *file, poll_table *wait)
 	 *  peasycap, IN WHICH CASE A REPEAT CALL TO isdongle() WILL FAIL.
 	 *  IF NECESSARY, BAIL OUT.
 	 */
-		if (kd != isdongle(peasycap))
+		if (kd != isdongle(peasycap)) {
+			mutex_unlock(&easycapdc60_dongle[kd].mutex_video);
 			return -ERESTARTSYS;
+		}
 		if (!file) {
 			SAY("ERROR:  file is NULL\n");
 			mutex_unlock(&easycapdc60_dongle[kd].mutex_video);
-- 
1.7.4.1

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