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Date: Tue, 05 Dec 2017 23:30:19 +0100
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From: Takashi Iwai <tiwai@suse.de>
To: Kees Cook <keescook@chromium.org>
Cc: Nick Desaulniers <ndesaulniers@google.com>,
        moderated for non-subscribers <alsa-devel@alsa-project.org>,
        Arvind Yadav <arvind.yadav.cs@gmail.com>,
        Robb Glasser <rglasser@google.com>, Jaroslav Kysela <perex@perex.cz>,
        Takashi Sakamoto <o-takashi@sakamocchi.jp>,
        Markus Elfring <elfring@users.sourceforge.net>,
        LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] ALSA: pcm: prevent UAF in snd_pcm_info
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On Tue, 05 Dec 2017 20:29:07 +0100,
Kees Cook wrote:
> 
> On Tue, Dec 5, 2017 at 11:14 AM, Takashi Iwai <tiwai@suse.de> wrote:
> > On Tue, 05 Dec 2017 18:16:55 +0100,
> > Nick Desaulniers wrote:
> >>
> >> From: Robb Glasser <rglasser@google.com>
> >>
> >> 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`.
> >>
> >> Signed-off-by: Robb Glasser <rglasser@google.com>
> >> Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
> >
> > Looks reasonable.  Applied with Cc to stable now.
> 
> FWIW, this was assigned CVE-2017-0861. (Best to get it into the commit
> log if possible.)

OK, I updated the changelog.  Thanks for information.


Takashi