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

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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: ea44d19076 ("usbip: Implement SG support to vhci-hcd and stub driver")
Reported-by: kbuild test robot <lkp@intel.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Suwan Kim <suwan.kim027@gmail.com>
Acked-by: Shuah 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: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Suwan Kim 2019-11-11 23:10:35 +09:00 committed by Greg Kroah-Hartman
parent 1ec13abac5
commit 2a9125317b
1 changed files with 32 additions and 18 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

50
drivers/usb/usbip/stub_rx.c
View File

@ -470,18 +470,50 @@ 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;
/* Check if the server's HCD supports SG */
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.
*/
support_sg = 0;
num_urbs = nents;
priv->completed_urbs = 0;
pdu->u.cmd_submit.transfer_flags &=
~URB_DMA_MAP_SG;
}
} else {
buffer = kzalloc(buf_len, GFP_KERNEL);
if (!buffer)
@ -489,24 +521,6 @@ static void stub_recv_cmd_submit(struct stub_device *sdev,
}
}
/* Check if the server's HCD supports SG */
if (use_sg && !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.
*/
support_sg = 0;
num_urbs = nents;
priv->completed_urbs = 0;
pdu->u.cmd_submit.transfer_flags &= ~URB_DMA_MAP_SG;
}
/* allocate urb array */
priv->num_urbs = num_urbs;
priv->urbs = kmalloc_array(num_urbs, sizeof(*priv->urbs), GFP_KERNEL);