linux-kernel - Re: [PATCH v2] media: uvcvideo: Fix OOB read

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Message-ID: <20230726080753.GX31069@pendragon.ideasonboard.com>
Date:   Wed, 26 Jul 2023 11:07:53 +0300
From:   Laurent Pinchart <laurent.pinchart@...asonboard.com>
To:     Ricardo Ribalda <ribalda@...omium.org>
Cc:     Mauro Carvalho Chehab <mchehab@...nel.org>,
        linux-media@...r.kernel.org, linux-kernel@...r.kernel.org,
        Sergey Senozhatsky <senozhatsky@...omium.org>,
        stable@...nel.org, Zubin Mithra <zsm@...omium.org>,
        Kai Wasserbäch <kai@....carbon-project.org>,
        Thorsten Leemhuis <linux@...mhuis.info>
Subject: Re: [PATCH v2] media: uvcvideo: Fix OOB read

Hi Ricardo,

(CC'ing Kai and Thorsten who have added the check to checkpatch)

On Wed, Jul 26, 2023 at 08:24:50AM +0200, Ricardo Ribalda wrote:
> On Tue, 25 Jul 2023 at 23:34, Laurent Pinchart wrote:
> > On Thu, Jul 20, 2023 at 05:46:54PM +0000, Ricardo Ribalda wrote:
> > > If the index provided by the user is bigger than the mask size, we might do an
> > > out of bound read.
> > >
> > > CC: stable@...nel.org
> > > Fixes: 40140eda661e ("media: uvcvideo: Implement mask for V4L2_CTRL_TYPE_MENU")
> > > Reported-by: Zubin Mithra <zsm@...omium.org>
> >
> > checkpatch now requests a Reported-by tag to be immediately followed by
> > a Closes tag that contains the URL to the report. Could you please
> > provide that ?
>
> I saw that, but the URL is kind of private:
> 
> Closes: http://issuetracker.google.com/issues/289975230

Ah :-S I wonder if we should drop the Reported-by tag then ?

> > > Signed-off-by: Ricardo Ribalda <ribalda@...omium.org>
> > > ---
> > > Avoid reading index >= 31
> > > ---
> > > Changes in v2:
> > > - Use BITS_PER_TYPE instead of 32 (thanks Sergey).
> > > - Add Reported-by tag.
> > > - Link to v1: https://lore.kernel.org/r/20230717-uvc-oob-v1-1-f5b9b4aba3b4@chromium.org
> > > ---
> > >  drivers/media/usb/uvc/uvc_ctrl.c | 3 +++
> > >  1 file changed, 3 insertions(+)
> > >
> > > diff --git a/drivers/media/usb/uvc/uvc_ctrl.c b/drivers/media/usb/uvc/uvc_ctrl.c
> > > index 5e9d3da862dd..e59a463c2761 100644
> > > --- a/drivers/media/usb/uvc/uvc_ctrl.c
> > > +++ b/drivers/media/usb/uvc/uvc_ctrl.c
> > > @@ -1402,6 +1402,9 @@ int uvc_query_v4l2_menu(struct uvc_video_chain *chain,
> > >       query_menu->id = id;
> > >       query_menu->index = index;
> > >
> > > +     if (index >= BITS_PER_TYPE(mapping->menu_mask))
> > > +             return -EINVAL;
> > > +
> >
> > I'd move this a few lines up, before setting query_menu.
> 
> SGTM, I just wanted to clear all the fields to mimic the other error
> paths of the function.

I'm fine with that too if you prefer.

> > With those minor changes,
> >
> > Reviewed-by: Laurent Pinchart <laurent.pinchart@...asonboard.com>
> >
> > There's no need for a v3, I can handle the changes locally, but I need
> > the URL for the Closes tag.
> >
> > >       ret = mutex_lock_interruptible(&chain->ctrl_mutex);
> > >       if (ret < 0)
> > >               return -ERESTARTSYS;
> > >
> > > ---
> > > base-commit: fdf0eaf11452d72945af31804e2a1048ee1b574c
> > > change-id: 20230717-uvc-oob-4b0148a00417

-- 
Regards,

Laurent Pinchart