linux-kernel - [PATCH] media: ttusb-dec: avoid release of non-acquired mutex

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Date:   Tue, 20 Jul 2021 12:28:27 +0300
From:   Evgeny Novikov <novikov@...ras.ru>
To:     Mauro Carvalho Chehab <mchehab@...nel.org>
Cc:     Evgeny Novikov <novikov@...ras.ru>,
        Hans Verkuil <hverkuil-cisco@...all.nl>,
        dingsenjie <dingsenjie@...ong.com>,
        Allen Pais <allen.lkml@...il.com>, linux-media@...r.kernel.org,
        linux-kernel@...r.kernel.org, ldv-project@...uxtesting.org
Subject: [PATCH] media: ttusb-dec: avoid release of non-acquired mutex

ttusb_dec_send_command() invokes mutex_lock_interruptible() that can
fail but then it releases the non-acquired mutex. The patch fixes that.

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

Fixes: dba328bab4c6 ("media: ttusb-dec: cleanup an error handling logic")
Signed-off-by: Evgeny Novikov <novikov@...ras.ru>
---
 drivers/media/usb/ttusb-dec/ttusb_dec.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/drivers/media/usb/ttusb-dec/ttusb_dec.c b/drivers/media/usb/ttusb-dec/ttusb_dec.c
index bfda46a36dc5..38822cedd93a 100644
--- a/drivers/media/usb/ttusb-dec/ttusb_dec.c
+++ b/drivers/media/usb/ttusb-dec/ttusb_dec.c
@@ -327,7 +327,7 @@ static int ttusb_dec_send_command(struct ttusb_dec *dec, const u8 command,
 	result = mutex_lock_interruptible(&dec->usb_mutex);
 	if (result) {
 		printk("%s: Failed to lock usb mutex.\n", __func__);
-		goto err;
+		goto err_free;
 	}
 
 	b[0] = 0xaa;
@@ -349,7 +349,7 @@ static int ttusb_dec_send_command(struct ttusb_dec *dec, const u8 command,
 	if (result) {
 		printk("%s: command bulk message failed: error %d\n",
 		       __func__, result);
-		goto err;
+		goto err_mutex_unlock;
 	}
 
 	result = usb_bulk_msg(dec->udev, dec->result_pipe, b,
@@ -358,7 +358,7 @@ static int ttusb_dec_send_command(struct ttusb_dec *dec, const u8 command,
 	if (result) {
 		printk("%s: result bulk message failed: error %d\n",
 		       __func__, result);
-		goto err;
+		goto err_mutex_unlock;
 	} else {
 		if (debug) {
 			printk(KERN_DEBUG "%s: result: %*ph\n",
@@ -371,9 +371,9 @@ static int ttusb_dec_send_command(struct ttusb_dec *dec, const u8 command,
 			memcpy(cmd_result, &b[4], b[3]);
 	}
 
-err:
+err_mutex_unlock:
 	mutex_unlock(&dec->usb_mutex);
-
+err_free:
 	kfree(b);
 	return result;
 }
-- 
2.26.2