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ALSA: pcm: Abort properly at pending signal in OSS read/write loops

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The loops for read and write in PCM OSS emulation have no proper check
of pending signals, and they keep processing even after user tries to
break.  This results in a very long delay, often seen as RCU stall
when a huge unprocessed bytes remain queued.  The bug could be easily
triggered by syzkaller.

As a simple workaround, this patch adds the proper check of pending
signals and aborts the loop appropriately.

Reported-by: syzbot+993cb4cfcbbff3947c21@syzkaller.appspotmail.com
Cc: <stable@vger.kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
This commit is contained in:
Takashi Iwai 2018-01-08 13:58:31 +01:00
parent 898dfe4687
commit 29159a4ed7
1 changed files with 8 additions and 0 deletions
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8
sound/core/oss/pcm_oss.c
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@ -1381,6 +1381,10 @@ static ssize_t snd_pcm_oss_write1(struct snd_pcm_substream *substream, const cha
tmp != runtime->oss.period_bytes)
break;
}
if (signal_pending(current)) {
tmp = -ERESTARTSYS;
goto err;
}
}
mutex_unlock(&runtime->oss.params_lock);
return xfer;
@ -1466,6 +1470,10 @@ static ssize_t snd_pcm_oss_read1(struct snd_pcm_substream *substream, char __use
bytes -= tmp;
xfer += tmp;
}
if (signal_pending(current)) {
tmp = -ERESTARTSYS;
goto err;
}
}
mutex_unlock(&runtime->oss.params_lock);
return xfer;