[PATCH AUTOSEL 5.18 31/39] ALSA: pcm: Use deferred fasync helper

Sasha Levin
2022-08-14T16:33:44Z

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);
}

/*
--
2.35.1