This is a note to let you know that I've just added the patch titled
ALSA: seq: Fix race at timer setup and close
to the 4.4-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-timer-setup-and-close.patch
and it can be found in the queue-4.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 3567eb6af614dac436c4b16a8d426f9faed639b3 Mon Sep 17 00:00:00 2001
From: Takashi Iwai <tiwai@xxxxxxx>
Date: Tue, 12 Jan 2016 15:36:27 +0100
Subject: ALSA: seq: Fix race at timer setup and close
From: Takashi Iwai <tiwai@xxxxxxx>
commit 3567eb6af614dac436c4b16a8d426f9faed639b3 upstream.
ALSA sequencer code has an open race between the timer setup ioctl and
the close of the client. This was triggered by syzkaller fuzzer, and
a use-after-free was caught there as a result.
This patch papers over it by adding a proper queue->timer_mutex lock
around the timer-related calls in the relevant code path.
Reported-by: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Tested-by: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Signed-off-by: Takashi Iwai <tiwai@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
sound/core/seq/seq_queue.c | 2 ++
1 file changed, 2 insertions(+)
--- a/sound/core/seq/seq_queue.c
+++ b/sound/core/seq/seq_queue.c
@@ -142,8 +142,10 @@ static struct snd_seq_queue *queue_new(i
static void queue_delete(struct snd_seq_queue *q)
{
/* stop and release the timer */
+ mutex_lock(&q->timer_mutex);
snd_seq_timer_stop(q->timer);
snd_seq_timer_close(q);
+ mutex_unlock(&q->timer_mutex);
/* wait until access free */
snd_use_lock_sync(&q->use_lock);
/* release resources... */
Patches currently in stable-queue which might be from tiwai@xxxxxxx are
queue-4.4/alsa-hrtimer-fix-stall-by-hrtimer_cancel.patch
queue-4.4/alsa-hda-fix-white-noise-on-dell-latitude-e5550.patch
queue-4.4/alsa-hda-fix-the-headset-mic-detection-problem-for-a-dell-laptop.patch
queue-4.4/alsa-timer-harden-slave-timer-list-handling.patch
queue-4.4/alsa-timer-fix-double-unlink-of-active_list.patch
queue-4.4/alsa-control-avoid-kernel-warnings-from-tlv-ioctl-with-numid-0.patch
queue-4.4/alsa-hda-flush-the-pending-probe-work-at-remove.patch
queue-4.4/alsa-hda-fixup-inverted-internal-mic-for-lenovo-e50-80.patch
queue-4.4/alsa-usb-add-native-dsd-support-for-oppo-ha-1.patch
queue-4.4/alsa-hda-fix-missing-module-loading-with-model-generic-option.patch
queue-4.4/alsa-seq-fix-race-at-timer-setup-and-close.patch
queue-4.4/alsa-pcm-fix-snd_pcm_hw_params-struct-copy-in-compat-mode.patch
queue-4.4/alsa-seq-fix-snd_seq_call_port_info_ioctl-in-compat-mode.patch
queue-4.4/alsa-seq-fix-missing-null-check-at-remove_events-ioctl.patch
queue-4.4/alsa-usb-audio-fix-mixer-ctl-regression-of-native-instrument-devices.patch
queue-4.4/alsa-timer-handle-disconnection-more-safely.patch
queue-4.4/alsa-hda-fix-bass-pin-fixup-for-asus-n550jx.patch
queue-4.4/alsa-timer-fix-race-among-timer-ioctls.patch
queue-4.4/alsa-hda-add-fixup-for-dell-latitidue-e6540.patch
queue-4.4/alsa-usb-audio-avoid-calling-usb_autopm_put_interface-at-disconnect.patch
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