Patch "ALSA: timer: Fix leftover link at closing" has been added to the 3.10-stable tree

[<gregkh@linuxfoundation.org>]

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

    ALSA: timer: Fix leftover link at closing

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-timer-fix-leftover-link-at-closing.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 <stable@vger.kernel.org> know about it.


>From 094fd3be87b0f102589e2d5c3fa5d06b7e20496d Mon Sep 17 00:00:00 2001
From: Takashi Iwai <tiwai@suse.de>
Date: Thu, 4 Feb 2016 17:06:13 +0100
Subject: ALSA: timer: Fix leftover link at closing

From: Takashi Iwai <tiwai@suse.de>

commit 094fd3be87b0f102589e2d5c3fa5d06b7e20496d upstream.

In ALSA timer core, the active timer instance is managed in
active_list linked list.  Each element is added / removed dynamically
at timer start, stop and in timer interrupt.  The problem is that
snd_timer_interrupt() has a thinko and leaves the element in
active_list when it's the last opened element.  This eventually leads
to list corruption or use-after-free error.

This hasn't been revealed because we used to delete the list forcibly
in snd_timer_stop() in the past.  However, the recent fix avoids the
double-stop behavior (in commit [f784beb75ce8: ALSA: timer: Fix link
corruption due to double start or stop]), and this leak hits reality.

This patch fixes the link management in snd_timer_interrupt().  Now it
simply unlinks no matter which stream is.

BugLink: http://lkml.kernel.org/r/CACT4Y+Yy2aukHP-EDp8-ziNqNNmb-NTf=jDWXMP7jB8HDa2vng@mail.gmail.com
Reported-by: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 sound/core/timer.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/sound/core/timer.c
+++ b/sound/core/timer.c
@@ -702,8 +702,8 @@ void snd_timer_interrupt(struct snd_time
 			ti->cticks = ti->ticks;
 		} else {
 			ti->flags &= ~SNDRV_TIMER_IFLG_RUNNING;
-			if (--timer->running)
-				list_del_init(&ti->active_list);
+			--timer->running;
+			list_del_init(&ti->active_list);
 		}
 		if ((timer->hw.flags & SNDRV_TIMER_HW_TASKLET) ||
 		    (ti->flags & SNDRV_TIMER_IFLG_FAST))


Patches currently in stable-queue which might be from tiwai@suse.de 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