From: Takashi Iwai tiwai@suse.de

[ Upstream commit 95cc637c1afd83fb7dd3d7c8a53710488f4caf9c ]

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

Reported-by: syzbot+1ee0910eca9c94f71f25@syzkaller.appspotmail.com Reported-by: syzbot+49b10793b867871ee26f@syzkaller.appspotmail.com Reported-by: syzbot+8285e973a41b5aa68902@syzkaller.appspotmail.com Link: https://lore.kernel.org/r/20220728125945.29533-3-tiwai@suse.de Signed-off-by: Takashi Iwai tiwai@suse.de Signed-off-by: Sasha Levin sashal@kernel.org --- sound/core/timer.c | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/sound/core/timer.c b/sound/core/timer.c index b3214baa8919..e08a37c23add 100644 --- a/sound/core/timer.c +++ b/sound/core/timer.c @@ -83,7 +83,7 @@ struct snd_timer_user { unsigned int filter; struct timespec64 tstamp; /* trigger tstamp */ wait_queue_head_t qchange_sleep; - struct fasync_struct *fasync; + struct snd_fasync *fasync; struct mutex ioctl_lock; };

@@ -1345,7 +1345,7 @@ static void snd_timer_user_interrupt(struct snd_timer_instance *timeri, } __wake: spin_unlock(&tu->qlock); - kill_fasync(&tu->fasync, SIGIO, POLL_IN); + snd_kill_fasync(tu->fasync, SIGIO, POLL_IN); wake_up(&tu->qchange_sleep); }

@@ -1383,7 +1383,7 @@ static void snd_timer_user_ccallback(struct snd_timer_instance *timeri, spin_lock_irqsave(&tu->qlock, flags); snd_timer_user_append_to_tqueue(tu, &r1); spin_unlock_irqrestore(&tu->qlock, flags); - kill_fasync(&tu->fasync, SIGIO, POLL_IN); + snd_kill_fasync(tu->fasync, SIGIO, POLL_IN); wake_up(&tu->qchange_sleep); }

@@ -1453,7 +1453,7 @@ static void snd_timer_user_tinterrupt(struct snd_timer_instance *timeri, spin_unlock(&tu->qlock); if (append == 0) return; - kill_fasync(&tu->fasync, SIGIO, POLL_IN); + snd_kill_fasync(tu->fasync, SIGIO, POLL_IN); wake_up(&tu->qchange_sleep); }

@@ -1521,6 +1521,7 @@ static int snd_timer_user_release(struct inode *inode, struct file *file) snd_timer_instance_free(tu->timeri); } mutex_unlock(&tu->ioctl_lock); + snd_fasync_free(tu->fasync); kfree(tu->queue); kfree(tu->tqueue); kfree(tu); @@ -2135,7 +2136,7 @@ static int snd_timer_user_fasync(int fd, struct file * file, int on) struct snd_timer_user *tu;

tu = file->private_data; - return fasync_helper(fd, file, on, &tu->fasync); + return snd_fasync_helper(fd, file, on, &tu->fasync); }

static ssize_t snd_timer_user_read(struct file *file, char __user *buffer,