linux-kernel - [PATCH 1/1] Media: radio: si470x: remove double mutex lock

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-next>] [day] [month] [year] [list]

Date:	Sun, 23 Jan 2011 12:16:54 +0300
From:	Alexander Strakh <cromlehg@...il.com>
To:	mchehab@...radead.org
Cc:	tobias.lorenz@....net, jy0922.shim@...sung.com,
	linux-media@...r.kernel.org, linux-kernel@...r.kernel.org,
	Alexander Strakh <cromlehg@...il.com>,
	Alexander Strakh <strakh@...ras.ru>
Subject: [PATCH 1/1] Media: radio: si470x: remove double mutex lock

From: Alexander Strakh <cromlehg@...il.com>


1. First mutex_lock on &radio->lock in line 441
2. Second in line 462

I think that mutex in line 462 is not needed. In kernel v2.6.36.3 function si470
x_rds_on contains mutex_lock/mutex_unlock. Have no mutex_lock in line 441. In kernel v2.6.37 mutex_lock/mutex_unlock has been moved from si470x_rds_on to fops_read. But old mutex_lock (line 462) forgot to remove. 

 433static ssize_t si470x_fops_read(struct file *file, char __user *buf,
 434                size_t count, loff_t *ppos)
 435{
....
 441        mutex_lock(&radio->lock);
 442        if ((radio->registers[SYSCONFIG1] & SYSCONFIG1_RDS) == 0)
 443                si470x_rds_on(radio);
 444
 445        /* block if no new data available */
 446        while (radio->wr_index == radio->rd_index) {
 447                if (file->f_flags & O_NONBLOCK) {
 448                        retval = -EWOULDBLOCK;
 449                        goto done;
 450                }
 451                if (wait_event_interruptible(radio->read_queue,
 452                        radio->wr_index != radio->rd_index) < 0) {
 453                        retval = -EINTR;
 454                        goto done;
 455                }
 456        }
 457
 458        /* calculate block count from byte count */
 459        count /= 3;
 460
 461        /* copy RDS block out of internal buffer and to user buffer */
 462        mutex_lock(&radio->lock);

Found by Linux Device Drivers Verification Project

Remove second mutex_lock from fops_read

Signed-off-by: Alexander Strakh <strakh@...ras.ru>
---
 drivers/media/radio/si470x/radio-si470x-common.c |    1 -
 1 files changed, 0 insertions(+), 1 deletions(-)

diff --git a/drivers/media/radio/si470x/radio-si470x-common.c b/drivers/media/radio/si470x/radio-si470x-common.c
index 60c176f..38ae6cd 100644
--- a/drivers/media/radio/si470x/radio-si470x-common.c
+++ b/drivers/media/radio/si470x/radio-si470x-common.c
@@ -460,7 +460,6 @@ static ssize_t si470x_fops_read(struct file *file, char __user *buf,
 	count /= 3;
 
 	/* copy RDS block out of internal buffer and to user buffer */
-	mutex_lock(&radio->lock);
 	while (block_count < count) {
 		if (radio->rd_index == radio->wr_index)
 			break;
-- 
1.7.1

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/