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author | Alexey Khoroshilov <khoroshilov@ispras.ru> | 2015-04-18 02:53:25 +0300 |
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committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2015-05-17 09:51:33 -0700 |
commit | cccea7f5c40ef96866d02be01e0712985940d102 (patch) | |
tree | b4ab3543f79d3b86b05cf44230be9954e0906184 /kernel | |
parent | 6186ada9e4801a27068373fae01d089e41054823 (diff) | |
download | edison-v3.10-cccea7f5c40ef96866d02be01e0712985940d102.tar.gz |
sound/oss: fix deadlock in sequencer_ioctl(SNDCTL_SEQ_OUTOFBAND)
commit bc26d4d06e337ade069f33d3f4377593b24e6e36 upstream.
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>
Cc: Willy Tarreau <w@1wt.eu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'kernel')
0 files changed, 0 insertions, 0 deletions