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authorTakashi Iwai <tiwai@suse.de>2016-02-04 17:06:13 +0100
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2016-02-17 12:30:59 -0800
commit43d2ac7b542a862b55d22d179468df5290590801 (patch)
treefd9a39999cc8fd3c7e5d0981aa75175e3c65c9d9 /sound/core
parent3f75d8ad63e42d5e1f46bd7fc2ba643cda3aa5e7 (diff)
ALSA: timer: Fix leftover link at closing
commit 094fd3be87b0f102589e2d5c3fa5d06b7e20496d upstream. In ALSA timer core, the active timer instance is managed in active_list linked list. Each element is added / removed dynamically at timer start, stop and in timer interrupt. The problem is that snd_timer_interrupt() has a thinko and leaves the element in active_list when it's the last opened element. This eventually leads to list corruption or use-after-free error. This hasn't been revealed because we used to delete the list forcibly in snd_timer_stop() in the past. However, the recent fix avoids the double-stop behavior (in commit [f784beb75ce8: ALSA: timer: Fix link corruption due to double start or stop]), and this leak hits reality. This patch fixes the link management in snd_timer_interrupt(). Now it simply unlinks no matter which stream is. BugLink: http://lkml.kernel.org/r/CACT4Y+Yy2aukHP-EDp8-ziNqNNmb-NTf=jDWXMP7jB8HDa2vng@mail.gmail.com Reported-by: Dmitry Vyukov <dvyukov@google.com> Signed-off-by: Takashi Iwai <tiwai@suse.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'sound/core')
-rw-r--r--sound/core/timer.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/sound/core/timer.c b/sound/core/timer.c
index 681fb051b9eb..b036e080382c 100644
--- a/sound/core/timer.c
+++ b/sound/core/timer.c
@@ -718,8 +718,8 @@ void snd_timer_interrupt(struct snd_timer * timer, unsigned long ticks_left)
ti->cticks = ti->ticks;
} else {
ti->flags &= ~SNDRV_TIMER_IFLG_RUNNING;
- if (--timer->running)
- list_del_init(&ti->active_list);
+ --timer->running;
+ list_del_init(&ti->active_list);
}
if ((timer->hw.flags & SNDRV_TIMER_HW_TASKLET) ||
(ti->flags & SNDRV_TIMER_IFLG_FAST))