Patch "ALSA: seq: Fix race at closing in virmidi driver" has been added to the 3.10-stable tree

This is a note to let you know that I've just added the patch titled

ALSA: seq: Fix race at closing in virmidi driver

to the 3.10-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
alsa-seq-fix-race-at-closing-in-virmidi-driver.patch
and it can be found in the queue-3.10 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Takashi Iwai <[email protected]>
Date: Mon, 1 Feb 2016 12:06:42 +0100
Subject: ALSA: seq: Fix race at closing in virmidi driver

From: Takashi Iwai <[email protected]>

commit 2d1b5c08366acd46c35a2e9aba5d650cb5bf5c19 upstream.

The virmidi driver has an open race at closing its assigned rawmidi device, and this may lead to use-after-free in snd_seq_deliver_single_event().

Plug the hole by properly protecting the linked list deletion and calling in the right order in snd_virmidi_input_close().

---
 sound/core/seq/seq_virmidi.c |    6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

@@ -254,9 +254,13 @@ static int snd_virmidi_output_open(struc
  */
 static int snd_virmidi_input_close(struct snd_rawmidi_substream *substream)
 {
+	struct snd_virmidi_dev *rdev = substream->rmidi->private_data;
 	struct snd_virmidi *vmidi = substream->runtime->private_data;
-	snd_midi_event_free(vmidi->parser);
+
+	write_lock_irq(&rdev->filelist_lock);
 	list_del(&vmidi->list);
+	write_unlock_irq(&rdev->filelist_lock);
+	snd_midi_event_free(vmidi->parser);
 	substream->runtime->private_data = NULL;
 	kfree(vmidi);
 	return 0;

Patches currently in stable-queue which might be from [email protected] are

queue-3.10/alsa-seq-fix-race-at-closing-in-virmidi-driver.patch queue-3.10/alsa-rawmidi-remove-kernel-warning-for-null-user-space-buffer-check.patch queue-3.10/alsa-seq-fix-lockdep-warnings-due-to-double-mutex-locks.patch queue-3.10/alsa-usb-audio-fix-teac-ud-501-ud-503-nt-503-usb-delay.patch queue-3.10/alsa-timer-fix-wrong-instance-passed-to-slave-callbacks.patch queue-3.10/alsa-compress-disable-get_codec_caps-ioctl-for-some-architectures.patch queue-3.10/alsa-hda-fix-speaker-output-from-vaio-aio-machines.patch queue-3.10/alsa-dummy-implement-timer-backend-switching-more-safely.patch queue-3.10/alsa-dummy-disable-switching-timer-backend-via-sysfs.patch queue-3.10/alsa-seq-fix-incorrect-sanity-check-at-snd_seq_oss_synth_cleanup.patch queue-3.10/alsa-seq-fix-yet-another-races-among-alsa-timer-accesses.patch queue-3.10/alsa-usb-audio-avoid-freeing-umidi-object-twice.patch queue-3.10/alsa-timer-fix-leftover-link-at-closing.patch queue-3.10/alsa-rawmidi-fix-race-at-copying-updating-the-position.patch queue-3.10/alsa-pcm-fix-potential-deadlock-in-oss-emulation.patch queue-3.10/alsa-timer-fix-link-corruption-due-to-double-start-or-stop.patch