This is a note to let you know that I've just added the patch titled ALSA: seq: Remove spurious WARN_ON() at timer check to the 4.9-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-remove-spurious-warn_on-at-timer-check.patch and it can be found in the queue-4.9 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From 43a3542870328601be02fcc9d27b09db467336ef Mon Sep 17 00:00:00 2001 From: Takashi Iwai <tiwai@xxxxxxx> Date: Thu, 30 Nov 2017 10:08:28 +0100 Subject: ALSA: seq: Remove spurious WARN_ON() at timer check From: Takashi Iwai <tiwai@xxxxxxx> commit 43a3542870328601be02fcc9d27b09db467336ef upstream. The use of snd_BUG_ON() in ALSA sequencer timer may lead to a spurious WARN_ON() when a slave timer is deployed as its backend and a corresponding master timer stops meanwhile. The symptom was triggered by syzkaller spontaneously. Since the NULL timer is valid there, rip off snd_BUG_ON(). Reported-by: syzbot <syzkaller@xxxxxxxxxxxxxxxx> Signed-off-by: Takashi Iwai <tiwai@xxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- sound/core/seq/seq_timer.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/sound/core/seq/seq_timer.c +++ b/sound/core/seq/seq_timer.c @@ -355,7 +355,7 @@ static int initialize_timer(struct snd_s unsigned long freq; t = tmr->timeri->timer; - if (snd_BUG_ON(!t)) + if (!t) return -EINVAL; freq = tmr->preferred_resolution; Patches currently in stable-queue which might be from tiwai@xxxxxxx are queue-4.9/alsa-seq-remove-spurious-warn_on-at-timer-check.patch queue-4.9/alsa-pcm-prevent-uaf-in-snd_pcm_info.patch queue-4.9/alsa-usb-audio-add-check-return-value-for-usb_string.patch queue-4.9/alsa-usb-audio-fix-out-of-bound-error.patch