From: Sasha Levin <sashal@kernel.org>
To: linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc: Takashi Iwai <tiwai@suse.de>, Sasha Levin <sashal@kernel.org>,
alsa-devel@alsa-project.org, paulhsia <paulhsia@chromium.org>
Subject: [alsa-devel] [PATCH AUTOSEL 4.14 11/21] ALSA: pcm: Fix stream lock usage in snd_pcm_period_elapsed()
Date: Fri, 22 Nov 2019 14:49:21 -0500 [thread overview]
Message-ID: <20191122194931.24732-11-sashal@kernel.org> (raw)
In-Reply-To: <20191122194931.24732-1-sashal@kernel.org>
From: paulhsia <paulhsia@chromium.org>
[ Upstream commit f5cdc9d4003a2f66ea57b3edd3e04acc2b1a4439 ]
If the nullity check for `substream->runtime` is outside of the lock
region, it is possible to have a null runtime in the critical section
if snd_pcm_detach_substream is called right before the lock.
Signed-off-by: paulhsia <paulhsia@chromium.org>
Link: https://lore.kernel.org/r/20191112171715.128727-2-paulhsia@chromium.org
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
sound/core/pcm_lib.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)
diff --git a/sound/core/pcm_lib.c b/sound/core/pcm_lib.c
index 729a85a6211d6..80453266a2def 100644
--- a/sound/core/pcm_lib.c
+++ b/sound/core/pcm_lib.c
@@ -1803,11 +1803,14 @@ void snd_pcm_period_elapsed(struct snd_pcm_substream *substream)
struct snd_pcm_runtime *runtime;
unsigned long flags;
- if (PCM_RUNTIME_CHECK(substream))
+ if (snd_BUG_ON(!substream))
return;
- runtime = substream->runtime;
snd_pcm_stream_lock_irqsave(substream, flags);
+ if (PCM_RUNTIME_CHECK(substream))
+ goto _unlock;
+ runtime = substream->runtime;
+
if (!snd_pcm_running(substream) ||
snd_pcm_update_hw_ptr0(substream, 1) < 0)
goto _end;
@@ -1818,6 +1821,7 @@ void snd_pcm_period_elapsed(struct snd_pcm_substream *substream)
#endif
_end:
kill_fasync(&runtime->fasync, SIGIO, POLL_IN);
+ _unlock:
snd_pcm_stream_unlock_irqrestore(substream, flags);
}
EXPORT_SYMBOL(snd_pcm_period_elapsed);
--
2.20.1
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parent reply other threads:[~2019-11-22 19:51 UTC|newest]
Thread overview: expand[flat|nested] mbox.gz Atom feed
[parent not found: <20191122194931.24732-1-sashal@kernel.org>]
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