From 60c444b1c6af1cc3e0b34da57a5dd2d96d2d6da2 Mon Sep 17 00:00:00 2001 From: Takashi Iwai Date: Mon, 8 Jan 2018 13:58:31 +0100 Subject: [PATCH] ALSA: pcm: Abort properly at pending signal in OSS read/write loops commit 29159a4ed7044c52e3e2cf1a9fb55cec4745c60b upstream. 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 Signed-off-by: Takashi Iwai Signed-off-by: Ben Hutchings --- sound/core/oss/pcm_oss.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/sound/core/oss/pcm_oss.c b/sound/core/oss/pcm_oss.c index efae143cb63b..a02512b79085 100644 --- a/sound/core/oss/pcm_oss.c +++ b/sound/core/oss/pcm_oss.c @@ -1422,6 +1422,10 @@ 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; @@ -1507,6 +1511,10 @@ 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; -- 2.39.2