Commit 29159a4e authored Jan 08, 2018 by Takashi Iwai

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



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>

parent 898dfe46

sound/core/oss/pcm_oss.c

+8 −0

Original line number	Diff line number	Diff line
		@@ -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;