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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org,
        syzbot+a8d4acdad35e6bbca308@syzkaller.appspotmail.com,
        Oliver Neukum <oneukum@suse.com>,
        "David S. Miller" <davem@davemloft.net>
Subject: [PATCH 4.14 008/239] ax88172a: fix information leak on short answers
Date:   Tue, 19 Nov 2019 06:16:48 +0100
Message-Id: <20191119051259.171362433@linuxfoundation.org>
In-Reply-To: <20191119051255.850204959@linuxfoundation.org>
References: <20191119051255.850204959@linuxfoundation.org>
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From: Oliver Neukum <oneukum@suse.com>

[ Upstream commit a9a51bd727d141a67b589f375fe69d0e54c4fe22 ]

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/net/usb/ax88172a.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/net/usb/ax88172a.c
+++ b/drivers/net/usb/ax88172a.c
@@ -208,7 +208,7 @@ static int ax88172a_bind(struct usbnet *
 
 	/* 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;
 	}