[PATCH 4.9 05/29] usbnet: make sure no NULL pointer is passed through

[Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>]

From: Oliver Neukum <oneukum@xxxxxxxx>

commit 6c22fce07c97f765af1808ec3be007847e0b47d1 upstream.

Coverity reports:

** CID 751368:  Null pointer dereferences  (FORWARD_NULL)
/drivers/net/usb/usbnet.c: 1925 in __usbnet_read_cmd()

________________________________________________________________________________________________________
---
 drivers/net/usb/usbnet.c |   19 +++++++++++++++----
 1 file changed, 15 insertions(+), 4 deletions(-)

--- a/drivers/net/usb/usbnet.c
+++ b/drivers/net/usb/usbnet.c
@@ -1951,7 +1951,7 @@ static int __usbnet_read_cmd(struct usbn
 		   " value=0x%04x index=0x%04x size=%d\n",
 		   cmd, reqtype, value, index, size);
 
-	if (data) {
+	if (size) {
 		buf = kmalloc(size, GFP_KERNEL);
 		if (!buf)
 			goto out;
@@ -1960,8 +1960,13 @@ static int __usbnet_read_cmd(struct usbn
 	err = usb_control_msg(dev->udev, usb_rcvctrlpipe(dev->udev, 0),
 			      cmd, reqtype, value, index, buf, size,
 			      USB_CTRL_GET_TIMEOUT);
-	if (err > 0 && err <= size)
-		memcpy(data, buf, err);
+	if (err > 0 && err <= size) {
+        if (data)
+            memcpy(data, buf, err);
+        else
+            netdev_dbg(dev->net,
+                "Huh? Data requested but thrown away.\n");
+    }
 	kfree(buf);
 out:
 	return err;
@@ -1982,7 +1987,13 @@ static int __usbnet_write_cmd(struct usb
 		buf = kmemdup(data, size, GFP_KERNEL);
 		if (!buf)
 			goto out;
-	}
+	} else {
+        if (size) {
+            WARN_ON_ONCE(1);
+            err = -EINVAL;
+            goto out;
+        }
+    }
 
 	err = usb_control_msg(dev->udev, usb_sndctrlpipe(dev->udev, 0),
 			      cmd, reqtype, value, index, buf, size,