ax88172a: fix information leak on short answers

If a malicious device gives a short MAC it can elicit up to
5 bytes of leaked memory out of the driver. We need to check for
ETH_ALEN instead.

Reported-by: syzbot+a8d4acdad35e6bbca308@syzkaller.appspotmail.com
Signed-off-by: Oliver Neukum <oneukum@suse.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/usb/ax88172a.c b/drivers/net/usb/ax88172a.c
index 011bd4c..af3994e 100644 (file)
--- a/drivers/net/usb/ax88172a.c
+++ b/drivers/net/usb/ax88172a.c
@@ -196,7 +196,7 @@ static int ax88172a_bind(struct usbnet *dev, struct usb_interface *intf)
 
        /* Get the MAC address */
        ret = asix_read_cmd(dev, AX_CMD_READ_NODE_ID, 0, 0, ETH_ALEN, buf, 0);
-       if (ret < 0) {
+       if (ret < ETH_ALEN) {
                netdev_err(dev->net, "Failed to read MAC address: %d\n", ret);
                goto free;
        }