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ALSA: seq: Protect in-kernel ioctl calls with mutex
authorTakashi Iwai <tiwai@suse.de>
Tue, 9 Apr 2019 15:35:22 +0000 (17:35 +0200)
committerTakashi Iwai <tiwai@suse.de>
Tue, 9 Apr 2019 16:54:12 +0000 (18:54 +0200)
commitfeb689025fbb6f0aa6297d3ddf97de945ea4ad32
tree47404a3ee86fa26298233e346c5a05341e6f4088
parentf823b8a75527dca0b93cf577bbabbe47fd79b2a8
ALSA: seq: Protect in-kernel ioctl calls with mutex

ALSA OSS sequencer calls the ioctl function indirectly via
snd_seq_kernel_client_ctl().  While we already applied the protection
against races between the normal ioctls and writes via the client's
ioctl_mutex, this code path was left untouched.  And this seems to be
the cause of still remaining some rare UAF as spontaneously triggered
by syzkaller.

For the sake of robustness, wrap the ioctl_mutex also for the call via
snd_seq_kernel_client_ctl(), too.

Reported-by: syzbot+e4c8abb920efa77bace9@syzkaller.appspotmail.com
Signed-off-by: Takashi Iwai <tiwai@suse.de>
sound/core/seq/seq_clientmgr.c