ALSA: timer: Fix wrong instance passed to slave callbacks

In snd_timer_notify1(), the wrong timer instance was passed for slave
ccallback function.  This leads to the access to the wrong data when
an incompatible master is handled (e.g. the master is the sequencer
timer and the slave is a user timer), as spotted by syzkaller fuzzer.

This patch fixes that wrong assignment.

BugLink: http://lkml.kernel.org/r/CACT4Y+Y_Bm+7epAb=8Wi=AaWd+DYS7qawX52qxdCfOfY49vozQ@mail.gmail.com
Reported-by: Dmitry Vyukov <dvyukov@google.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

diff --git a/sound/core/timer.c b/sound/core/timer.c
index 9b513a0..dea932a 100644 (file)
--- a/sound/core/timer.c
+++ b/sound/core/timer.c
@@ -422,7 +422,7 @@ static void snd_timer_notify1(struct snd_timer_instance *ti, int event)
        spin_lock_irqsave(&timer->lock, flags);
        list_for_each_entry(ts, &ti->slave_active_head, active_list)
                if (ts->ccallback)
-                       ts->ccallback(ti, event + 100, &tstamp, resolution);
+                       ts->ccallback(ts, event + 100, &tstamp, resolution);
        spin_unlock_irqrestore(&timer->lock, flags);
 }