From: Takashi Iwai tiwai@suse.de

[ Upstream commit 96b097091c66df4f6fbf5cbff21df6cc02a2f055 ]

For avoiding the potential deadlock via kill_fasync() call, use the new fasync helpers to defer the invocation from timer API. Note that it's merely a workaround.

Reported-by: syzbot+8285e973a41b5aa68902@syzkaller.appspotmail.com Reported-by: syzbot+669c9abf11a6a011dd09@syzkaller.appspotmail.com Link: https://lore.kernel.org/r/20220728125945.29533-4-tiwai@suse.de Signed-off-by: Takashi Iwai tiwai@suse.de Signed-off-by: Sasha Levin sashal@kernel.org --- include/sound/pcm.h | 2 +- sound/core/pcm.c | 1 + sound/core/pcm_lib.c | 2 +- sound/core/pcm_native.c | 2 +- 4 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/include/sound/pcm.h b/include/sound/pcm.h index 6b99310b5b88..6987110843f0 100644 --- a/include/sound/pcm.h +++ b/include/sound/pcm.h @@ -399,7 +399,7 @@ struct snd_pcm_runtime { snd_pcm_uframes_t twake; /* do transfer (!poll) wakeup if non-zero */ wait_queue_head_t sleep; /* poll sleep */ wait_queue_head_t tsleep; /* transfer sleep */ - struct fasync_struct *fasync; + struct snd_fasync *fasync; bool stop_operating; /* sync_stop will be called */ struct mutex buffer_mutex; /* protect for buffer changes */ atomic_t buffer_accessing; /* >0: in r/w operation, <0: blocked */ diff --git a/sound/core/pcm.c b/sound/core/pcm.c index 977d54320a5c..c917ac84a7e5 100644 --- a/sound/core/pcm.c +++ b/sound/core/pcm.c @@ -1005,6 +1005,7 @@ void snd_pcm_detach_substream(struct snd_pcm_substream *substream) substream->runtime = NULL; } mutex_destroy(&runtime->buffer_mutex); + snd_fasync_free(runtime->fasync); kfree(runtime); put_pid(substream->pid); substream->pid = NULL; diff --git a/sound/core/pcm_lib.c b/sound/core/pcm_lib.c index 1fc7c50ffa62..40751e5aff09 100644 --- a/sound/core/pcm_lib.c +++ b/sound/core/pcm_lib.c @@ -1822,7 +1822,7 @@ void snd_pcm_period_elapsed_under_stream_lock(struct snd_pcm_substream *substrea snd_timer_interrupt(substream->timer, 1); #endif _end: - kill_fasync(&runtime->fasync, SIGIO, POLL_IN); + snd_kill_fasync(runtime->fasync, SIGIO, POLL_IN); } EXPORT_SYMBOL(snd_pcm_period_elapsed_under_stream_lock);

diff --git a/sound/core/pcm_native.c b/sound/core/pcm_native.c index 4adaee62ef33..16fcf57c6f03 100644 --- a/sound/core/pcm_native.c +++ b/sound/core/pcm_native.c @@ -3945,7 +3945,7 @@ static int snd_pcm_fasync(int fd, struct file * file, int on) runtime = substream->runtime; if (runtime->status->state == SNDRV_PCM_STATE_DISCONNECTED) return -EBADFD; - return fasync_helper(fd, file, on, &runtime->fasync); + return snd_fasync_helper(fd, file, on, &runtime->fasync); }

/*