Re: [PATCH v2] usb: gadget: uvc: Fix ERR_PTR dereference in uvc_v4l2.c

Greg KH
2024-08-15T08:00:36Z

On Thu, Aug 15, 2024 at 12:44:16PM +0530, Abhishek Tamboli wrote:
> Fix potential dereferencing of ERR_PTR() in find_format_by_pix()
> and uvc_v4l2_enum_format().
>
> Fix the following smatch errors:
>
> drivers/usb/gadget/function/uvc_v4l2.c:124 find_format_by_pix()
> error: 'fmtdesc' dereferencing possible ERR_PTR()
>
> drivers/usb/gadget/function/uvc_v4l2.c:392 uvc_v4l2_enum_format()
> error: 'fmtdesc' dereferencing possible ERR_PTR()
>
> Also, fix similar issue in uvc_v4l2_try_format() for potential
> dereferencing of ERR_PTR().
>
> Fixes: 588b9e85609b ("usb: gadget: uvc: add v4l2 enumeration api calls")
> Fixes: e219a712bc06 ("usb: gadget: uvc: add v4l2 try_format api call")
> Signed-off-by: Abhishek Tamboli <abhishektamboli9@gmail.com>
> ---
> Changes in v2:
> - Add check for dereferencing of ERR_PTR() in uvc_v4l2_try_format()
>
> drivers/usb/gadget/function/uvc_v4l2.c | 12 +++++++++++-
> 1 file changed, 11 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/usb/gadget/function/uvc_v4l2.c b/drivers/usb/gadget/function/uvc_v4l2.c
> index a024aecb76dc..8bb88c864b60 100644
> --- a/drivers/usb/gadget/function/uvc_v4l2.c
> +++ b/drivers/usb/gadget/function/uvc_v4l2.c
> @@ -121,6 +121,9 @@ static struct uvcg_format *find_format_by_pix(struct uvc_device *uvc,
> list_for_each_entry(format, &uvc->header->formats, entry) {
> const struct uvc_format_desc *fmtdesc = to_uvc_format(format->fmt);
>
> + if (IS_ERR(fmtdesc))
> + continue;
> +
> if (fmtdesc->fcc == pixelformat) {
> uformat = format->fmt;
> break;
> @@ -240,6 +243,7 @@ uvc_v4l2_try_format(struct file *file, void *fh, struct v4l2_format *fmt)
> struct uvc_video *video = &uvc->video;
> struct uvcg_format *uformat;
> struct uvcg_frame *uframe;
> + const struct uvc_format_desc *fmtdesc;
> u8 *fcc;
>
> if (fmt->type != video->queue.queue.type)
> @@ -277,7 +281,10 @@ uvc_v4l2_try_format(struct file *file, void *fh, struct v4l2_format *fmt)
> fmt->fmt.pix.height = uframe->frame.w_height;
> fmt->fmt.pix.bytesperline = uvc_v4l2_get_bytesperline(uformat, uframe);
> fmt->fmt.pix.sizeimage = uvc_get_frame_size(uformat, uframe);
> - fmt->fmt.pix.pixelformat = to_uvc_format(uformat)->fcc;
> + fmtdesc = to_uvc_format(uformat);
> + if (IS_ERR(fmtdesc))
> + return -EINVAL;

Why not return the error given to you?

> + fmt->fmt.pix.pixelformat = fmtdesc->fcc;
> }
> fmt->fmt.pix.field = V4L2_FIELD_NONE;
> fmt->fmt.pix.colorspace = V4L2_COLORSPACE_SRGB;
> @@ -389,6 +396,9 @@ uvc_v4l2_enum_format(struct file *file, void *fh, struct v4l2_fmtdesc *f)
> return -EINVAL;
>
> fmtdesc = to_uvc_format(uformat);
> + if (IS_ERR(fmtdesc))
> + return -EINVAL;

Same here.

thanks,

greg k-h