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authorTakashi Iwai <tiwai@suse.de>2016-04-14 18:02:37 +0200
committerBen Hutchings <ben@decadent.org.uk>2017-02-23 03:51:06 +0000
commit5409b6c1f1b38d3fb461704d02addf55119c5230 (patch)
tree389a2c6a9fe01e42eb03db0936b127d446b554bd
parentc516724814d826ae1a90849e24e386c2ad81a845 (diff)
ALSA: pcm : Call kill_fasync() in stream lock
commit 3aa02cb664c5fb1042958c8d1aa8c35055a2ebc4 upstream. Currently kill_fasync() is called outside the stream lock in snd_pcm_period_elapsed(). This is potentially racy, since the stream may get released even during the irq handler is running. Although snd_pcm_release_substream() calls snd_pcm_drop(), this doesn't guarantee that the irq handler finishes, thus the kill_fasync() call outside the stream spin lock may be invoked after the substream is detached, as recently reported by KASAN. As a quick workaround, move kill_fasync() call inside the stream lock. The fasync is rarely used interface, so this shouldn't have a big impact from the performance POV. Ideally, we should implement some sync mechanism for the proper finish of stream and irq handler. But this oneliner should suffice for most cases, so far. Reported-by: Baozeng Ding <sploving1@gmail.com> Signed-off-by: Takashi Iwai <tiwai@suse.de> [bwh: Backported to 3.2: adjust context] Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
-rw-r--r--sound/core/pcm_lib.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/sound/core/pcm_lib.c b/sound/core/pcm_lib.c
index 7f00d34f0abd..b36544a62b40 100644
--- a/sound/core/pcm_lib.c
+++ b/sound/core/pcm_lib.c
@@ -1766,10 +1766,10 @@ void snd_pcm_period_elapsed(struct snd_pcm_substream *substream)
if (substream->timer_running)
snd_timer_interrupt(substream->timer, 1);
_end:
- snd_pcm_stream_unlock_irqrestore(substream, flags);
if (runtime->transfer_ack_end)
runtime->transfer_ack_end(substream);
kill_fasync(&runtime->fasync, SIGIO, POLL_IN);
+ snd_pcm_stream_unlock_irqrestore(substream, flags);
}
EXPORT_SYMBOL(snd_pcm_period_elapsed);