[dm-devel] [PATCH stable] dm ioctl: fix out of bounds array access when no devices

[Ard Biesheuvel]

On Wed, 19 May 2021 at 16:56, Sasha Levin <sashal at kernel.org> wrote:
>
> On Wed, May 19, 2021 at 09:41:24AM +0200, Ard Biesheuvel wrote:
> >From: Mikulas Patocka <mpatocka at redhat.com>
> >
> >commit 4edbe1d7bcffcd6269f3b5eb63f710393ff2ec7a upstream.
> >
> >If there are not any dm devices, we need to zero the "dev" argument in
> >the first structure dm_name_list. However, this can cause out of
> >bounds write, because the "needed" variable is zero and len may be
> >less than eight.
> >
> >Fix this bug by reporting DM_BUFFER_FULL_FLAG if the result buffer is
> >too small to hold the "nl->dev" value.
> >
> >Signed-off-by: Mikulas Patocka <mpatocka at redhat.com>
> >Reported-by: Dan Carpenter <dan.carpenter at oracle.com>
> >Cc: stable at vger.kernel.org
> >Signed-off-by: Mike Snitzer <snitzer at redhat.com>
> >Signed-off-by: Ard Biesheuvel <ardb at kernel.org>
> >---
> >Please apply to 4.4.y and 4.9.y
>
> We already carry this patch via the backport provided in
> https://lore.kernel.org/stable/20210513094552.266451-1-nobuhiro1.iwamatsu@toshiba.co.jp/
>

Excellent, thanks.