On Wed, May 26, 2021 at 11:32:44AM -0400, Alan Stern wrote:
> A type of inconsistency that can show up in control URBs is when the
> setup packet's wLength value does not match the URB's
> transfer_buffer_length field. The two should always be equal;
> differences could lead to information leaks or undefined behavior for
> OUT transfers or overruns for IN transfers.
>
> This patch adds a test for such mismatches during URB submission. If
> the test fails, the submission is rejected with a -EBADR error code
> (which is not used elsewhere in the USB core), and a debugging message
> is logged for people interested in tracking down these errors.
>
> Signed-off-by: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
> CC: Johan Hovold <johan@xxxxxxxxxx>
Looks good.
Reviewed-by: Johan Hovold <johan@xxxxxxxxxx>
> ---
>
>
> [as1961]
>
>
> Documentation/driver-api/usb/error-codes.rst | 3 +++
> drivers/usb/core/urb.c | 6 ++++++
> 2 files changed, 9 insertions(+)
>
> Index: usb-devel/drivers/usb/core/urb.c
> ===================================================================
> --- usb-devel.orig/drivers/usb/core/urb.c
> +++ usb-devel/drivers/usb/core/urb.c
> @@ -410,6 +410,12 @@ int usb_submit_urb(struct urb *urb, gfp_
> dev_WARN_ONCE(&dev->dev, (usb_pipeout(urb->pipe) != is_out),
> "BOGUS control dir, pipe %x doesn't match bRequestType %x\n",
> urb->pipe, setup->bRequestType);
> + if (le16_to_cpu(setup->wLength) != urb->transfer_buffer_length) {
> + dev_dbg(&dev->dev, "BOGUS control len %d doesn't match transfer length %d\n",
> + le16_to_cpu(setup->wLength),
> + urb->transfer_buffer_length);
> + return -EBADR;
> + }
> } else {
> is_out = usb_endpoint_dir_out(&ep->desc);
> }
> Index: usb-devel/Documentation/driver-api/usb/error-codes.rst
> ===================================================================
> --- usb-devel.orig/Documentation/driver-api/usb/error-codes.rst
> +++ usb-devel/Documentation/driver-api/usb/error-codes.rst
> @@ -61,6 +61,9 @@ USB-specific:
> (c) requested data transfer length is invalid: negative
> or too large for the host controller.
>
> +``-EBADR`` The wLength value in a control URB's setup packet does
> + not match the URB's transfer_buffer_length.
> +
> ``-ENOSPC`` This request would overcommit the usb bandwidth reserved
> for periodic transfers (interrupt, isochronous).
>
