]> git.proxmox.com Git - mirror_ubuntu-eoan-kernel.git/commit
ALSA: timer: Fix race between stop and interrupt
authorTakashi Iwai <tiwai@suse.de>
Tue, 9 Feb 2016 11:02:32 +0000 (12:02 +0100)
committerTakashi Iwai <tiwai@suse.de>
Tue, 9 Feb 2016 11:02:32 +0000 (12:02 +0100)
commited8b1d6d2c741ab26d60d499d7fbb7ac801f0f51
tree1321d353d8fc88fa201ec6f27dfa7d32468e0b0d
parent117159f0b9d392fb433a7871426fad50317f06f7
ALSA: timer: Fix race between stop and interrupt

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.com
Cc: <stable@vger.kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
sound/core/timer.c