Commit 2a9a1964 authored by Foster Snowhill's avatar Foster Snowhill Committed by Paolo Abeni
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usbnet: ipheth: refactor NCM datagram loop 



Introduce an rx_error label to reduce repetitions in the header
signature checks.

Store wDatagramIndex and wDatagramLength after endianness conversion to
avoid repeated le16_to_cpu() calls.

Rewrite the loop to return on a null trailing DPE, which is required
by the CDC NCM spec. In case it is missing, fall through to rx_error.

This change does not fix any particular issue. Its purpose is to
simplify a subsequent commit that fixes a potential OoB read by limiting
the maximum amount of processed DPEs.

Cc: stable@vger.kernel.org # 6.5.x
Signed-off-by: default avatarFoster Snowhill <forst@pen.gy>
Reviewed-by: default avatarJakub Kicinski <kuba@kernel.org>
Signed-off-by: default avatarPaolo Abeni <pabeni@redhat.com>
parent 86586dcb

drivers/net/usb/ipheth.c

+23 −19
Original line number Diff line number Diff line
@@ -213,9 +213,9 @@ static int ipheth_rcvbulk_callback_ncm(struct urb *urb) 
	struct usb_cdc_ncm_ndp16 *ncm0;

	struct usb_cdc_ncm_dpe16 *dpe;

	struct ipheth_device *dev;

	u16 dg_idx, dg_len;

	int retval = -EINVAL;

	char *buf;

	int len;



	dev = urb->context;
@@ -227,39 +227,43 @@ static int ipheth_rcvbulk_callback_ncm(struct urb *urb) 
	ncmh = urb->transfer_buffer;

	if (ncmh->dwSignature != cpu_to_le32(USB_CDC_NCM_NTH16_SIGN) ||

	    /* On iOS, NDP16 directly follows NTH16 */

	    ncmh->wNdpIndex != cpu_to_le16(sizeof(struct usb_cdc_ncm_nth16))) {

		dev->net->stats.rx_errors++;

		return retval;

	}

	    ncmh->wNdpIndex != cpu_to_le16(sizeof(struct usb_cdc_ncm_nth16)))

		goto rx_error;



	ncm0 = urb->transfer_buffer + sizeof(struct usb_cdc_ncm_nth16);

	if (ncm0->dwSignature != cpu_to_le32(USB_CDC_NCM_NDP16_NOCRC_SIGN)) {

		dev->net->stats.rx_errors++;

		return retval;

	}

	if (ncm0->dwSignature != cpu_to_le32(USB_CDC_NCM_NDP16_NOCRC_SIGN))

		goto rx_error;



	dpe = ncm0->dpe16;

	while (le16_to_cpu(dpe->wDatagramIndex) != 0 &&

	       le16_to_cpu(dpe->wDatagramLength) != 0) {

		if (le16_to_cpu(dpe->wDatagramIndex) < IPHETH_NCM_HEADER_SIZE ||

		    le16_to_cpu(dpe->wDatagramIndex) >= urb->actual_length ||

		    le16_to_cpu(dpe->wDatagramLength) > urb->actual_length -

		    le16_to_cpu(dpe->wDatagramIndex)) {

	while (true) {

		dg_idx = le16_to_cpu(dpe->wDatagramIndex);

		dg_len = le16_to_cpu(dpe->wDatagramLength);



		/* Null DPE must be present after last datagram pointer entry

		 * (3.3.1 USB CDC NCM spec v1.0)

		 */

		if (dg_idx == 0 && dg_len == 0)

			return 0;



		if (dg_idx < IPHETH_NCM_HEADER_SIZE ||

		    dg_idx >= urb->actual_length ||

		    dg_len > urb->actual_length - dg_idx) {

			dev->net->stats.rx_length_errors++;

			return retval;

		}



		buf = urb->transfer_buffer + le16_to_cpu(dpe->wDatagramIndex);

		len = le16_to_cpu(dpe->wDatagramLength);

		buf = urb->transfer_buffer + dg_idx;



		retval = ipheth_consume_skb(buf, len, dev);

		retval = ipheth_consume_skb(buf, dg_len, dev);

		if (retval != 0)

			return retval;



		dpe++;

	}



	return 0;

rx_error:

	dev->net->stats.rx_errors++;

	return retval;

}



static void ipheth_rcvbulk_callback(struct urb *urb)