Commit 2a912531 authored by Suwan Kim's avatar Suwan Kim Committed by Greg Kroah-Hartman
Browse files

usbip: Fix uninitialized symbol 'nents' in stub_recv_cmd_submit() 



Smatch reported that nents is not initialized and used in
stub_recv_cmd_submit(). nents is currently initialized by sgl_alloc()
and used to allocate multiple URBs when host controller doesn't
support scatter-gather DMA. The use of uninitialized nents means that
buf_len is zero and use_sg is true. But buffer length should not be
zero when an URB uses scatter-gather DMA.

To prevent this situation, add the conditional that checks buf_len
and use_sg. And move the use of nents right after the sgl_alloc() to
avoid the use of uninitialized nents.

If the error occurs, it adds SDEV_EVENT_ERROR_MALLOC and stub_priv
will be released by stub event handler and connection will be shut
down.

Fixes: ea44d190 ("usbip: Implement SG support to vhci-hcd and stub driver")
Reported-by: default avatarkbuild test robot <lkp@intel.com>
Reported-by: default avatarDan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: default avatarSuwan Kim <suwan.kim027@gmail.com>
Acked-by: default avatarShuah Khan <skhan@linuxfoundation.org>
Cc: stable <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20191111141035.27788-1-suwan.kim027@gmail.com


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 1ec13aba

drivers/usb/usbip/stub_rx.c

+32 −18
Original line number Diff line number Diff line
@@ -470,41 +470,55 @@ static void stub_recv_cmd_submit(struct stub_device *sdev, 
	if (pipe == -1)

		return;



	/*

	 * Smatch reported the error case where use_sg is true and buf_len is 0.

	 * In this case, It adds SDEV_EVENT_ERROR_MALLOC and stub_priv will be

	 * released by stub event handler and connection will be shut down.

	 */

	priv = stub_priv_alloc(sdev, pdu);

	if (!priv)

		return;



	buf_len = (unsigned long long)pdu->u.cmd_submit.transfer_buffer_length;



	if (use_sg && !buf_len) {

		dev_err(&udev->dev, "sg buffer with zero length\n");

		goto err_malloc;

	}



	/* allocate urb transfer buffer, if needed */

	if (buf_len) {

		if (use_sg) {

			sgl = sgl_alloc(buf_len, GFP_KERNEL, &nents);

			if (!sgl)

				goto err_malloc;

		} else {

			buffer = kzalloc(buf_len, GFP_KERNEL);

			if (!buffer)

				goto err_malloc;

		}

	}



			/* Check if the server's HCD supports SG */

	if (use_sg && !udev->bus->sg_tablesize) {

			if (!udev->bus->sg_tablesize) {

				/*

		 * If the server's HCD doesn't support SG, break a single SG

		 * request into several URBs and map each SG list entry to

		 * corresponding URB buffer. The previously allocated SG

		 * list is stored in priv->sgl (If the server's HCD support SG,

		 * SG list is stored only in urb->sg) and it is used as an

		 * indicator that the server split single SG request into

		 * several URBs. Later, priv->sgl is used by stub_complete() and

		 * stub_send_ret_submit() to reassemble the divied URBs.

				 * If the server's HCD doesn't support SG, break

				 * a single SG request into several URBs and map

				 * each SG list entry to corresponding URB

				 * buffer. The previously allocated SG list is

				 * stored in priv->sgl (If the server's HCD

				 * support SG, SG list is stored only in

				 * urb->sg) and it is used as an indicator that

				 * the server split single SG request into

				 * several URBs. Later, priv->sgl is used by

				 * stub_complete() and stub_send_ret_submit() to

				 * reassemble the divied URBs.

				 */

				support_sg = 0;

				num_urbs = nents;

				priv->completed_urbs = 0;

		pdu->u.cmd_submit.transfer_flags &= ~URB_DMA_MAP_SG;

				pdu->u.cmd_submit.transfer_flags &=

								~URB_DMA_MAP_SG;

			}

		} else {

			buffer = kzalloc(buf_len, GFP_KERNEL);

			if (!buffer)

				goto err_malloc;

		}

	}



	/* allocate urb array */

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