linux-kernel - Re: [PATCH v1 1/1] media: uvc: Handle cameras with invalid descriptors

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Date:   Wed, 21 Sep 2022 09:51:44 +0200
From:   Ricardo Ribalda <ribalda@...omium.org>
To:     Laurent Pinchart <laurent.pinchart@...asonboard.com>
Cc:     Mauro Carvalho Chehab <mchehab@...nel.org>,
        linux-media@...r.kernel.org, linux-kernel@...r.kernel.org,
        syzbot <syzkaller@...glegroups.com>
Subject: Re: [PATCH v1 1/1] media: uvc: Handle cameras with invalid descriptors

Do you mean something like this?

diff --git a/drivers/media/usb/uvc/uvc_entity.c
b/drivers/media/usb/uvc/uvc_entity.c
index 7c4d2f93d351..66d1f5da4ec7 100644
--- a/drivers/media/usb/uvc/uvc_entity.c
+++ b/drivers/media/usb/uvc/uvc_entity.c
@@ -37,7 +37,7 @@ static int uvc_mc_create_links(struct uvc_video_chain *chain,
                        continue;

                remote = uvc_entity_by_id(chain->dev, entity->baSourceID[i]);
-               if (remote == NULL)
+               if (remote == NULL || remote->num_pads == 0)
                        return -EINVAL;

                source = (UVC_ENTITY_TYPE(remote) == UVC_TT_STREAMING)
@@ -46,6 +46,9 @@ static int uvc_mc_create_links(struct uvc_video_chain *chain,
                if (source == NULL)
                        continue;

+               if (source->num_pads != remote->num_pads)
+                       return -EINVAL;
+
                remote_pad = remote->num_pads - 1;
                ret = media_create_pad_link(source, remote_pad,
                                               sink, i, flags);

regarding making a new patch, whatever is easier for you ;)


On Wed, 21 Sept 2022 at 02:53, Laurent Pinchart
<laurent.pinchart@...asonboard.com> wrote:
>
> Hi Ricardo,
>
> Thank you for the patch.
>
> On Tue, Sep 20, 2022 at 04:04:55PM +0200, Ricardo Ribalda wrote:
> > If the source entity does not contain any pads, do not create a link.
> >
> > Reported-by: syzbot <syzkaller@...glegroups.com>
> > Signed-off-by: Ricardo Ribalda <ribalda@...omium.org>
> >
> > diff --git a/drivers/media/usb/uvc/uvc_entity.c b/drivers/media/usb/uvc/uvc_entity.c
> > index 7c4d2f93d351..1f730cb72e58 100644
> > --- a/drivers/media/usb/uvc/uvc_entity.c
> > +++ b/drivers/media/usb/uvc/uvc_entity.c
> > @@ -43,7 +43,7 @@ static int uvc_mc_create_links(struct uvc_video_chain *chain,
> >               source = (UVC_ENTITY_TYPE(remote) == UVC_TT_STREAMING)
> >                      ? (remote->vdev ? &remote->vdev->entity : NULL)
> >                      : &remote->subdev.entity;
> > -             if (source == NULL)
> > +             if (source == NULL || source->num_pads == 0)
>
> source->num_pads and remote->num_pads should always be identical, but as
> the next line uses remote->num_pads, wouldn't it be better to test that
> variable ? If so, I'd move the test a file lines earlier, with the
> remote == NULL test.
>
> What do you think ? If you agree I can make that change when applying,
> there's no need for a new version. Otherwise I'll keep the patch as-is.
>
> >                       continue;
> >
> >               remote_pad = remote->num_pads - 1;
> >
>
> --
> Regards,
>
> Laurent Pinchart



-- 
Ricardo Ribalda