The async signal (SIGIO) support for ALSA PCM API has been never used by real applications, but yet it can be a cause of various potential deadlocks, as spotted by syzkaller. Let's drop the feature as the simplest solution.
Reported-by: syzbot+8285e973a41b5aa68902@syzkaller.appspotmail.com Reported-by: syzbot+669c9abf11a6a011dd09@syzkaller.appspotmail.com Signed-off-by: Takashi Iwai tiwai@suse.de --- include/sound/pcm.h | 1 - sound/core/pcm_lib.c | 4 +--- sound/core/pcm_native.c | 18 ------------------ 3 files changed, 1 insertion(+), 22 deletions(-)
diff --git a/include/sound/pcm.h b/include/sound/pcm.h index 08cf4a5801f3..9bbd3742ef59 100644 --- a/include/sound/pcm.h +++ b/include/sound/pcm.h @@ -399,7 +399,6 @@ 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; 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_lib.c b/sound/core/pcm_lib.c index 1fc7c50ffa62..a7b10ee5d57d 100644 --- a/sound/core/pcm_lib.c +++ b/sound/core/pcm_lib.c @@ -1815,14 +1815,12 @@ void snd_pcm_period_elapsed_under_stream_lock(struct snd_pcm_substream *substrea
if (!snd_pcm_running(substream) || snd_pcm_update_hw_ptr0(substream, 1) < 0) - goto _end; + return;
#ifdef CONFIG_SND_PCM_TIMER if (substream->timer_running) snd_timer_interrupt(substream->timer, 1); #endif - _end: - 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 aa0453e51595..c8e340b97277 100644 --- a/sound/core/pcm_native.c +++ b/sound/core/pcm_native.c @@ -3938,22 +3938,6 @@ static int snd_pcm_mmap(struct file *file, struct vm_area_struct *area) return 0; }
-static int snd_pcm_fasync(int fd, struct file * file, int on) -{ - struct snd_pcm_file * pcm_file; - struct snd_pcm_substream *substream; - struct snd_pcm_runtime *runtime; - - pcm_file = file->private_data; - substream = pcm_file->substream; - if (PCM_RUNTIME_CHECK(substream)) - return -ENXIO; - runtime = substream->runtime; - if (runtime->status->state == SNDRV_PCM_STATE_DISCONNECTED) - return -EBADFD; - return fasync_helper(fd, file, on, &runtime->fasync); -} - /* * ioctl32 compat */ @@ -4118,7 +4102,6 @@ const struct file_operations snd_pcm_f_ops[2] = { .unlocked_ioctl = snd_pcm_ioctl, .compat_ioctl = snd_pcm_ioctl_compat, .mmap = snd_pcm_mmap, - .fasync = snd_pcm_fasync, .get_unmapped_area = snd_pcm_get_unmapped_area, }, { @@ -4132,7 +4115,6 @@ const struct file_operations snd_pcm_f_ops[2] = { .unlocked_ioctl = snd_pcm_ioctl, .compat_ioctl = snd_pcm_ioctl_compat, .mmap = snd_pcm_mmap, - .fasync = snd_pcm_fasync, .get_unmapped_area = snd_pcm_get_unmapped_area, } };