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: ea44d190764b ("usbip: Implement SG support to vhci-hcd and stub driver")
Reported-by: kbuild test robot <lkp@xxxxxxxxx>
Reported-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
Signed-off-by: Suwan Kim <suwan.kim027@xxxxxxxxx>
---
drivers/usb/usbip/stub_rx.c | 50 ++++++++++++++++++++++++-------------
1 file changed, 32 insertions(+), 18 deletions(-)
diff --git a/drivers/usb/usbip/stub_rx.c b/drivers/usb/usbip/stub_rx.c
index 66edfeea68fe..e2b019532234 100644
--- a/drivers/usb/usbip/stub_rx.c
+++ b/drivers/usb/usbip/stub_rx.c
@@ -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);
--
2.21.0
