The patch below does not apply to the 4.4-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From 3ab7992018455ac63c33e9b3eaa7264e293e40f4 Mon Sep 17 00:00:00 2001
From: Pavel Skripkin paskripkin@gmail.com Date: Sun, 24 Oct 2021 17:03:15 +0300 Subject: [PATCH] ALSA: mixer: fix deadlock in snd_mixer_oss_set_volume
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@syzkaller.appspotmail.com Fixes: 411cef6adfb3 ("ALSA: mixer: oss: Fix racy access to slots") Cc: stable@vger.kernel.org Signed-off-by: Pavel Skripkin paskripkin@gmail.com Link: https://lore.kernel.org/r/20211024140315.16704-1-paskripkin@gmail.com Signed-off-by: Takashi Iwai tiwai@suse.de
diff --git a/sound/core/oss/mixer_oss.c b/sound/core/oss/mixer_oss.c index d5ddc154a735..9620115cfdc0 100644 --- 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(struct snd_mixer_oss_file *fmixer, pslot->volume[1] = right; result = (left & 0xff) | ((right & 0xff) << 8); unlock: - mutex_lock(&mixer->reg_mutex); + mutex_unlock(&mixer->reg_mutex); return result; }