From: Takashi Iwai tiwai@suse.de
This patch has been added to the 4.1 stable tree. If you have any objections, please let us know.
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[ Upstream commit 29159a4ed7044c52e3e2cf1a9fb55cec4745c60b ]
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 Signed-off-by: Sasha Levin alexander.levin@microsoft.com --- 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 4a5bcf178982..d2a9e0fd46b0 100644 --- a/sound/core/oss/pcm_oss.c +++ b/sound/core/oss/pcm_oss.c @@ -1416,6 +1416,10 @@ 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; @@ -1501,6 +1505,10 @@ 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;