Re: [PATCH] usb: uvc: Fix 1-byte out-of-bounds read in uvc_parse_format()

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

On Tue, Jun 10, 2025 at 02:58:25PM +0200, Ricardo Ribalda wrote:
> Hi Youngjun
> 
> You still miss the v2 (v3 in this case). and the trailers.
> 
> In the future you can use the b4 tool to take care of most of the details.
> https://b4.docs.kernel.org/en/latest/contributor/overview.html
> It has "dry-run" option that let you review the mails before you send
> them to the mailing list
> 
> Please do not resubmit a new patch to fix this, only send a new patch
> to fix more comments for other people.
> 
> Regards!
> 
> On Tue, 10 Jun 2025 at 14:41, Youngjun Lee <yjjuny.lee@samsung.com> wrote:
> >
> > The buffer length check before calling uvc_parse_format() only ensured
> > that the buffer has at least 3 bytes (buflen > 2), buf the function
> > accesses buffer[3], requiring at least 4 bytes.
> >
> > This can lead to an out-of-bounds read if the buffer has exactly 3 bytes.
> >
> > Fix it by checking that the buffer has at least 4 bytes in
> > uvc_parse_format().
>
> Fixes: c0efd232929c ("V4L/DVB (8145a): USB Video Class driver")
> Cc: stable@vger.kernel.org
> Reviewed-by: Ricardo Ribalda <ribalda@chromium.org>

Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

> > Signed-off-by: Youngjun Lee <yjjuny.lee@samsung.com>
> > ---
> >  drivers/media/usb/uvc/uvc_driver.c | 3 +++
> >  1 file changed, 3 insertions(+)
> >
> > diff --git a/drivers/media/usb/uvc/uvc_driver.c b/drivers/media/usb/uvc/uvc_driver.c
> > index da24a655ab68..1100469a83a2 100644
> > --- a/drivers/media/usb/uvc/uvc_driver.c
> > +++ b/drivers/media/usb/uvc/uvc_driver.c
> > @@ -344,6 +344,9 @@ static int uvc_parse_format(struct uvc_device *dev,
> >         u8 ftype;
> >         int ret;
> >
> > +       if (buflen < 4)
> > +               return -EINVAL;
> > +
> >         format->type = buffer[2];
> >         format->index = buffer[3];
> >         format->frames = frames;

-- 
Regards,

Laurent Pinchart