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b13a4908f4
commit 411cef6adf upstream.
The OSS mixer can reassign the mapping slots dynamically via proc
file. Although the addition and deletion of those slots are protected
by mixer->reg_mutex, the access to slots aren't, hence this may cause
UAF when the slots in use are deleted concurrently.
This patch applies the mixer->reg_mutex in all appropriate code paths
(i.e. the ioctl functions) that may access slots.
Reported-by: syzbot+9988f17cf72a1045a189@syzkaller.appspotmail.com
Reviewed-by: Jaroslav Kysela <perex@perex.cz>
Cc: <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/00000000000036adc005ceca9175@google.com
Link: https://lore.kernel.org/r/20211020164846.922-1-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>