• Takashi Iwai's avatar
    ALSA: seq: More protection for concurrent write and ioctl races · 7bd80091
    Takashi Iwai authored
    This patch is an attempt for further hardening against races between
    the concurrent write and ioctls.  The previous fix d15d662e
    ("ALSA: seq: Fix racy pool initializations") covered the race of the
    pool initialization at writer and the pool resize ioctl by the
    client->ioctl_mutex (CVE-2018-1000004).  However, basically this mutex
    should be applied more widely to the whole write operation for
    avoiding the unexpected pool operations by another thread.
    The only change outside snd_seq_write() is the additional mutex
    argument to helper functions, so that we can unlock / relock the given
    mutex temporarily during schedule() call for blocking write.
    Fixes: d15d662e ("ALSA: seq: Fix racy pool initializations")
    Reported-by: default avatar范龙飞 <long7573@126.com>
    Reported-by: default avatarNicolai Stange <nstange@suse.de>
    Reviewed-and-tested-by: default avatarNicolai Stange <nstange@suse.de>
    Cc: <stable@vger.kernel.org>
    Signed-off-by: default avatarTakashi Iwai <tiwai@suse.de>
seq_memory.h 3.24 KB