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author | Takashi Iwai <tiwai@suse.de> | 2019-07-15 22:50:27 +0200 |
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committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-07-26 09:10:56 +0200 |
commit | a9865cf13a6edfedac84cc0d53023ca0a9267cfe (patch) | |
tree | f259e7e96a71faaac1bef55ebd15911648e6ce94 /sound/pci | |
parent | c7b5dbbacb0dace989c57a726aa68be72e746441 (diff) | |
download | linux-stable-a9865cf13a6edfedac84cc0d53023ca0a9267cfe.tar.gz linux-stable-a9865cf13a6edfedac84cc0d53023ca0a9267cfe.tar.bz2 linux-stable-a9865cf13a6edfedac84cc0d53023ca0a9267cfe.zip |
ALSA: seq: Break too long mutex context in the write loop
commit ede34f397ddb063b145b9e7d79c6026f819ded13 upstream.
The fix for the racy writes and ioctls to sequencer widened the
application of client->ioctl_mutex to the whole write loop. Although
it does unlock/relock for the lengthy operation like the event dup,
the loop keeps the ioctl_mutex for the whole time in other
situations. This may take quite long time if the user-space would
give a huge buffer, and this is a likely cause of some weird behavior
spotted by syzcaller fuzzer.
This patch puts a simple workaround, just adding a mutex break in the
loop when a large number of events have been processed. This
shouldn't hit any performance drop because the threshold is set high
enough for usual operations.
Fixes: 7bd800915677 ("ALSA: seq: More protection for concurrent write and ioctl races")
Reported-by: syzbot+97aae04ce27e39cbfca9@syzkaller.appspotmail.com
Reported-by: syzbot+4c595632b98bb8ffcc66@syzkaller.appspotmail.com
Cc: <stable@vger.kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'sound/pci')
0 files changed, 0 insertions, 0 deletions