diff options
| author | Alexey Khoroshilov <khoroshilov@ispras.ru> | 2015-04-18 02:53:25 +0300 |
|---|---|---|
| committer | Willy Tarreau <w@1wt.eu> | 2015-05-24 10:10:56 +0200 |
| commit | c8412c6c97217654c7a6d9b9030f7910ca9a0b82 (patch) | |
| tree | 88a475efc6adc58fcc07d2bfa8b2183229363146 | |
| parent | 533c1137c5ea83fcd59a0c5ec4b5e18e099677c0 (diff) | |
sound/oss: fix deadlock in sequencer_ioctl(SNDCTL_SEQ_OUTOFBAND)
A deadlock can be initiated by userspace via ioctl(SNDCTL_SEQ_OUTOFBAND)
on /dev/sequencer with TMR_ECHO midi event.
In this case the control flow is:
sound_ioctl()
-> case SND_DEV_SEQ:
case SND_DEV_SEQ2:
sequencer_ioctl()
-> case SNDCTL_SEQ_OUTOFBAND:
spin_lock_irqsave(&lock,flags);
play_event();
-> case EV_TIMING:
seq_timing_event()
-> case TMR_ECHO:
seq_copy_to_input()
-> spin_lock_irqsave(&lock,flags);
It seems that spin_lock_irqsave() around play_event() is not necessary,
because the only other call location in seq_startplay() makes the call
without acquiring spinlock.
So, the patch just removes spinlocks around play_event().
By the way, it removes unreachable code in seq_timing_event(),
since (seq_mode == SEQ_2) case is handled in the beginning.
Compile tested only.
Found by Linux Driver Verification project (linuxtesting.org).
Signed-off-by: Alexey Khoroshilov <khoroshilov@ispras.ru>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
(cherry picked from commit bc26d4d06e337ade069f33d3f4377593b24e6e36)
Signed-off-by: Willy Tarreau <w@1wt.eu>
| -rw-r--r-- | sound/oss/sequencer.c | 12 |
1 files changed, 2 insertions, 10 deletions
diff --git a/sound/oss/sequencer.c b/sound/oss/sequencer.c index 5cb171d903fb..7d32997652e0 100644 --- a/sound/oss/sequencer.c +++ b/sound/oss/sequencer.c @@ -677,13 +677,8 @@ static int seq_timing_event(unsigned char *event_rec) break; case TMR_ECHO: - if (seq_mode == SEQ_2) - seq_copy_to_input(event_rec, 8); - else - { - parm = (parm << 8 | SEQ_ECHO); - seq_copy_to_input((unsigned char *) &parm, 4); - } + parm = (parm << 8 | SEQ_ECHO); + seq_copy_to_input((unsigned char *) &parm, 4); break; default:; @@ -1326,7 +1321,6 @@ int sequencer_ioctl(int dev, struct file *file, unsigned int cmd, void __user *a int mode = translate_mode(file); struct synth_info inf; struct seq_event_rec event_rec; - unsigned long flags; int __user *p = arg; orig_dev = dev = dev >> 4; @@ -1481,9 +1475,7 @@ int sequencer_ioctl(int dev, struct file *file, unsigned int cmd, void __user *a case SNDCTL_SEQ_OUTOFBAND: if (copy_from_user(&event_rec, arg, sizeof(event_rec))) return -EFAULT; - spin_lock_irqsave(&lock,flags); play_event(event_rec.arr); - spin_unlock_irqrestore(&lock,flags); return 0; case SNDCTL_MIDI_INFO: |