[PATCH 3.13.y-ckt 069/138] ALSA: timer: Fix wrong instance passed to slave callbacks

From: Kamal Mostafa
Date: Wed Mar 09 2016 - 18:18:24 EST

3.13.11-ckt36 -stable review patch. If anyone has any objections, please let me know.


From: Takashi Iwai <tiwai@xxxxxxx>

commit 117159f0b9d392fb433a7871426fad50317f06f7 upstream.

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@xxxxxxxxxxxxxx
Reported-by: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Signed-off-by: Takashi Iwai <tiwai@xxxxxxx>
Signed-off-by: Kamal Mostafa <kamal@xxxxxxxxxxxxx>
sound/core/timer.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/sound/core/timer.c b/sound/core/timer.c
index 79e57a7..44cbdde 100644
--- a/sound/core/timer.c
+++ b/sound/core/timer.c
@@ -415,7 +415,7 @@ 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);