tree 59bbaf2321653f2c34522bf705e53aef8b9f7ffe
parent 0aa6ce52d38e3b4d257c9d314208f83781ef4854
author Takashi Iwai <tiwai@suse.de> 1581678794 +0100
committer Greg Kroah-Hartman <gregkh@linuxfoundation.org> 1582900975 +0100

ALSA: seq: Avoid concurrent access to queue flags

commit bb51e669fa49feb5904f452b2991b240ef31bc97 upstream.

The queue flags are represented in bit fields and the concurrent
access may result in unexpected results.  Although the current code
should be mostly OK as it's only reading a field while writing other
fields as KCSAN reported, it's safer to cover both with a proper
spinlock protection.

This patch fixes the possible concurrent read by protecting with
q->owner_lock.  Also the queue owner field is protected as well since
it's the field to be protected by the lock itself.

Reported-by: syzbot+65c6c92d04304d0a8efc@syzkaller.appspotmail.com
Reported-by: syzbot+e60ddfa48717579799dd@syzkaller.appspotmail.com
Link: https://lore.kernel.org/r/20200214111316.26939-2-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>