This is a note to let you know that I've just added the patch titled
ALSA: pcm: prevent UAF in snd_pcm_info
to the 4.14-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-pcm-prevent-uaf-in-snd_pcm_info.patch and it can be found in the queue-4.14 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 362bca57f5d78220f8b5907b875961af9436e229 Mon Sep 17 00:00:00 2001
From: Robb Glasser rglasser@google.com Date: Tue, 5 Dec 2017 09:16:55 -0800 Subject: ALSA: pcm: prevent UAF in snd_pcm_info
From: Robb Glasser rglasser@google.com
commit 362bca57f5d78220f8b5907b875961af9436e229 upstream.
When the device descriptor is closed, the `substream->runtime` pointer is freed. But another thread may be in the ioctl handler, case SNDRV_CTL_IOCTL_PCM_INFO. This case calls snd_pcm_info_user() which calls snd_pcm_info() which accesses the now freed `substream->runtime`.
Note: this fixes CVE-2017-0861
Signed-off-by: Robb Glasser rglasser@google.com Signed-off-by: Nick Desaulniers ndesaulniers@google.com Signed-off-by: Takashi Iwai tiwai@suse.de Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- sound/core/pcm.c | 2 ++ 1 file changed, 2 insertions(+)
--- a/sound/core/pcm.c +++ b/sound/core/pcm.c @@ -153,7 +153,9 @@ static int snd_pcm_control_ioctl(struct err = -ENXIO; goto _error; } + mutex_lock(&pcm->open_mutex); err = snd_pcm_info_user(substream, info); + mutex_unlock(&pcm->open_mutex); _error: mutex_unlock(®ister_mutex); return err;
Patches currently in stable-queue which might be from rglasser@google.com are
queue-4.14/alsa-pcm-prevent-uaf-in-snd_pcm_info.patch