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| author | Takashi Iwai <tiwai@suse.de> | 2016-02-04 17:06:13 +0100 |
|---|---|---|
| committer | Sasha Levin <sasha.levin@oracle.com> | 2016-02-15 15:45:34 -0500 |
| commit | 451e9d9111a2c83d46cdd48d5eea2fa8e8d72d9a (patch) | |
| tree | 04cd4da458603cac520f993b116255d18a4a1c9a | |
| parent | b35f45f2ebf224e06836ced6ccebb05ec700a6a9 (diff) | |
| download | lwn-451e9d9111a2c83d46cdd48d5eea2fa8e8d72d9a.tar.gz lwn-451e9d9111a2c83d46cdd48d5eea2fa8e8d72d9a.zip | |
ALSA: timer: Fix leftover link at closing
[ Upstream commit 094fd3be87b0f102589e2d5c3fa5d06b7e20496d ]
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>
Cc: <stable@vger.kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
| -rw-r--r-- | sound/core/timer.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/sound/core/timer.c b/sound/core/timer.c index 357e86f7804a..00e8c5f4de17 100644 --- a/sound/core/timer.c +++ b/sound/core/timer.c @@ -744,8 +744,8 @@ 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)) |