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| author | Takashi Iwai <tiwai@suse.de> | 2016-02-04 17:06:13 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2016-02-17 12:34:37 -0800 |
| commit | 3a43ddb85acf2bfb892cf29dd7a7ee3f8427d1fb (patch) | |
| tree | b47b8e1782788d108668263de4d5202bb9be22c1 | |
| parent | 5886e7b59075f4702015ba66cdacdc897e6e284a (diff) | |
| download | lwn-3a43ddb85acf2bfb892cf29dd7a7ee3f8427d1fb.tar.gz lwn-3a43ddb85acf2bfb892cf29dd7a7ee3f8427d1fb.zip | |
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>
| -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 987e4bc63186..a1385c7079f6 100644 --- a/sound/core/timer.c +++ b/sound/core/timer.c @@ -696,8 +696,8 @@ 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)) |