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Takashi Iwai authored
commit ed8b1d6d upstream. A slave timer element also unlinks at snd_timer_stop() but it takes only slave_active_lock. When a slave is assigned to a master, however, this may become a race against the master's interrupt handling, eventually resulting in a list corruption. The actual bug could be seen with a syzkaller fuzzer test case in BugLink below. As a fix, we need to take timeri->timer->lock when timer isn't NULL, i.e. assigned to a master, while the assignment to a master itself is protected by slave_active_lock. BugLink: http://lkml.kernel.org/r/CACT4Y+Y_Bm+7epAb=8Wi=AaWd+DYS7qawX52qxdCfOfY49vozQ@mail.gmail.comSigned-off-by: Takashi Iwai <tiwai@suse.de> [ kamal: backport to 3.13-stable: context ] Signed-off-by: Kamal Mostafa <kamal@canonical.com>
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