linux-kernel - [PATCH 5.4 096/355] ALSA: mixer: fix deadlock in snd_mixer_oss_set

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Message-Id: <20211115165316.903581870@linuxfoundation.org>
Date:   Mon, 15 Nov 2021 18:00:20 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        syzbot+ace149a75a9a0a399ac7@...kaller.appspotmail.com,
        Pavel Skripkin <paskripkin@...il.com>,
        Takashi Iwai <tiwai@...e.de>
Subject: [PATCH 5.4 096/355] ALSA: mixer: fix deadlock in snd_mixer_oss_set_volume

From: Pavel Skripkin <paskripkin@...il.com>

commit 3ab7992018455ac63c33e9b3eaa7264e293e40f4 upstream.

In commit 411cef6adfb3 ("ALSA: mixer: oss: Fix racy access to slots")
added mutex protection in snd_mixer_oss_set_volume(). Second
mutex_lock() in same function looks like typo, fix it.

Reported-by: syzbot+ace149a75a9a0a399ac7@...kaller.appspotmail.com
Fixes: 411cef6adfb3 ("ALSA: mixer: oss: Fix racy access to slots")
Cc: <stable@...r.kernel.org>
Signed-off-by: Pavel Skripkin <paskripkin@...il.com>
Link: https://lore.kernel.org/r/20211024140315.16704-1-paskripkin@gmail.com
Signed-off-by: Takashi Iwai <tiwai@...e.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 sound/core/oss/mixer_oss.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/sound/core/oss/mixer_oss.c
+++ b/sound/core/oss/mixer_oss.c
@@ -313,7 +313,7 @@ static int snd_mixer_oss_set_volume(stru
 	pslot->volume[1] = right;
 	result = (left & 0xff) | ((right & 0xff) << 8);
  unlock:
-	mutex_lock(&mixer->reg_mutex);
+	mutex_unlock(&mixer->reg_mutex);
 	return result;
 }