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Commit 400e6e32 authored by Takashi Iwai's avatar Takashi Iwai Committed by Ecco Park
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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: default avatarBaozeng Ding <sploving1@gmail.com>
Bug: 34068036
Signed-off-by: default avatarTakashi Iwai <tiwai@suse.de>
Signed-off-by: default avatarWilly Tarreau <w@1wt.eu>
Change-Id: Idd6a2de99d82699cc4f7cb619bf03566a10730ce
parent d7cb5337
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