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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 03:54:48 +0000
commitafd9c2402bdfdbc813587faf7f0e8e1f94c2ee91 (patch)
tree1e24e1392c37ce84a09fca5a71352fd5a2adb1a5 /sound
parent756826fd4e4a25589a2e77a7ceb791314c73cf48 (diff)
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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 3.16: adjust context] Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Diffstat (limited to 'sound')
-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 0032278567ad..0b4d286cbd3c 100644
--- a/sound/core/pcm_lib.c
+++ b/sound/core/pcm_lib.c
@@ -1856,10 +1856,10 @@ 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);