netdev - [PATCH] ax88172a: fix information leak on short answers

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Message-Id: <20191114101601.31734-1-oneukum@suse.com>
Date:   Thu, 14 Nov 2019 11:16:01 +0100
From:   Oliver Neukum <oneukum@...e.com>
To:     tglx@...utronix.de, allison@...utok.net, swinslow@...il.com,
        netdev@...r.kernel.org, davem@...emloft.net
Cc:     Oliver Neukum <oneukum@...e.com>
Subject: [PATCH] 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@...kaller.appspotmail.com
Signed-off-by: Oliver Neukum <oneukum@...e.com>
---
 drivers/net/usb/ax88172a.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/usb/ax88172a.c b/drivers/net/usb/ax88172a.c
index 011bd4cb546e..af3994e0853b 100644
--- 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;
 	}
-- 
2.16.4