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

ALSA: aloop: Release cable upon open error path

to the 4.4-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...

The filename of the patch is: alsa-aloop-release-cable-upon-open-error-path.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@vger.kernel.org know about it.

From 9685347aa0a5c2869058ca6ab79fd8e93084a67f Mon Sep 17 00:00:00 2001

From: Takashi Iwai tiwai@suse.de Date: Fri, 5 Jan 2018 16:09:47 +0100 Subject: ALSA: aloop: Release cable upon open error path

From: Takashi Iwai tiwai@suse.de

commit 9685347aa0a5c2869058ca6ab79fd8e93084a67f upstream.

The aloop runtime object and its assignment in the cable are left even when opening a substream fails. This doesn't mean any memory leak, but it still keeps the invalid pointer that may be referred by the another side of the cable spontaneously, which is a potential Oops cause.

Clean up the cable assignment and the empty cable upon the error path properly.

Fixes: 597603d615d2 ("ALSA: introduce the snd-aloop module for the PCM loopback") Signed-off-by: Takashi Iwai tiwai@suse.de Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org

--- sound/drivers/aloop.c | 38 +++++++++++++++++++++++++------------- 1 file changed, 25 insertions(+), 13 deletions(-)

--- a/sound/drivers/aloop.c +++ b/sound/drivers/aloop.c @@ -658,12 +658,31 @@ static int rule_channels(struct snd_pcm_ return snd_interval_refine(hw_param_interval(params, rule->var), &t); }

+static void free_cable(struct snd_pcm_substream *substream) +{ + struct loopback *loopback = substream->private_data; + int dev = get_cable_index(substream); + struct loopback_cable *cable; + + cable = loopback->cables[substream->number][dev]; + if (!cable) + return; + if (cable->streams[!substream->stream]) { + /* other stream is still alive */ + cable->streams[substream->stream] = NULL; + } else { + /* free the cable */ + loopback->cables[substream->number][dev] = NULL; + kfree(cable); + } +} + static int loopback_open(struct snd_pcm_substream *substream) { struct snd_pcm_runtime *runtime = substream->runtime; struct loopback *loopback = substream->private_data; struct loopback_pcm *dpcm; - struct loopback_cable *cable; + struct loopback_cable *cable = NULL; int err = 0; int dev = get_cable_index(substream);

@@ -682,7 +701,6 @@ static int loopback_open(struct snd_pcm_ if (!cable) { cable = kzalloc(sizeof(*cable), GFP_KERNEL); if (!cable) { - kfree(dpcm); err = -ENOMEM; goto unlock; } @@ -724,6 +742,10 @@ static int loopback_open(struct snd_pcm_ else runtime->hw = cable->hw; unlock: + if (err < 0) { + free_cable(substream); + kfree(dpcm); + } mutex_unlock(&loopback->cable_lock); return err; } @@ -732,20 +754,10 @@ static int loopback_close(struct snd_pcm { struct loopback *loopback = substream->private_data; struct loopback_pcm *dpcm = substream->runtime->private_data; - struct loopback_cable *cable; - int dev = get_cable_index(substream);

loopback_timer_stop(dpcm); mutex_lock(&loopback->cable_lock); - cable = loopback->cables[substream->number][dev]; - if (cable->streams[!substream->stream]) { - /* other stream is still alive */ - cable->streams[substream->stream] = NULL; - } else { - /* free the cable */ - loopback->cables[substream->number][dev] = NULL; - kfree(cable); - } + free_cable(substream); mutex_unlock(&loopback->cable_lock); return 0; }

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

queue-4.4/alsa-pcm-remove-incorrect-snd_bug_on-usages.patch queue-4.4/alsa-aloop-fix-inconsistent-format-due-to-incomplete-rule.patch queue-4.4/alsa-pcm-add-missing-error-checks-in-oss-emulation-plugin-builder.patch queue-4.4/alsa-pcm-abort-properly-at-pending-signal-in-oss-read-write-loops.patch queue-4.4/alsa-pcm-allow-aborting-mutex-lock-at-oss-read-write-loops.patch queue-4.4/alsa-aloop-fix-racy-hw-constraints-adjustment.patch queue-4.4/alsa-aloop-release-cable-upon-open-error-path.patch