linux-kernel - [PATCH 5.4 83/85] net: usb: rtl8150: set random MAC address when set_ethernet

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Date:   Mon, 12 Oct 2020 15:27:46 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        syzbot+abbc768b560c84d92fd3@...kaller.appspotmail.com,
        Petko Manolov <petkan@...leusys.com>,
        Anant Thazhemadam <anant.thazhemadam@...il.com>,
        "David S. Miller" <davem@...emloft.net>
Subject: [PATCH 5.4 83/85] net: usb: rtl8150: set random MAC address when set_ethernet_addr() fails

From: Anant Thazhemadam <anant.thazhemadam@...il.com>

commit f45a4248ea4cc13ed50618ff066849f9587226b2 upstream.

When get_registers() fails in set_ethernet_addr(),the uninitialized
value of node_id gets copied over as the address.
So, check the return value of get_registers().

If get_registers() executed successfully (i.e., it returns
sizeof(node_id)), copy over the MAC address using ether_addr_copy()
(instead of using memcpy()).

Else, if get_registers() failed instead, a randomly generated MAC
address is set as the MAC address instead.

Reported-by: syzbot+abbc768b560c84d92fd3@...kaller.appspotmail.com
Tested-by: syzbot+abbc768b560c84d92fd3@...kaller.appspotmail.com
Acked-by: Petko Manolov <petkan@...leusys.com>
Signed-off-by: Anant Thazhemadam <anant.thazhemadam@...il.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/net/usb/rtl8150.c |   16 ++++++++++++----
 1 file changed, 12 insertions(+), 4 deletions(-)

--- a/drivers/net/usb/rtl8150.c
+++ b/drivers/net/usb/rtl8150.c
@@ -274,12 +274,20 @@ static int write_mii_word(rtl8150_t * de
 		return 1;
 }

-static inline void set_ethernet_addr(rtl8150_t * dev)
+static void set_ethernet_addr(rtl8150_t *dev)
 {
-	u8 node_id[6];
+	u8 node_id[ETH_ALEN];
+	int ret;

-	get_registers(dev, IDR, sizeof(node_id), node_id);
-	memcpy(dev->netdev->dev_addr, node_id, sizeof(node_id));
+	ret = get_registers(dev, IDR, sizeof(node_id), node_id);
+
+	if (ret == sizeof(node_id)) {
+		ether_addr_copy(dev->netdev->dev_addr, node_id);
+	} else {
+		eth_hw_addr_random(dev->netdev);
+		netdev_notice(dev->netdev, "Assigned a random MAC address: %pM\n",
+			      dev->netdev->dev_addr);
+	}
 }

 static int rtl8150_set_mac_address(struct net_device *netdev, void *p)