netdev - [PATCH] net: usb: rtl8150: don't incorrectly assign random MAC addresses

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Date:   Sat, 10 Oct 2020 12:14:59 +0530
From:   Anant Thazhemadam <anant.thazhemadam@...il.com>
To:     unlisted-recipients:; (no To-header on input)
Cc:     linux-kernel-mentees@...ts.linuxfoundation.org,
        Anant Thazhemadam <anant.thazhemadam@...il.com>,
        Petko Manolov <petkan@...leusys.com>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>, linux-usb@...r.kernel.org,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH] net: usb: rtl8150: don't incorrectly assign random MAC addresses

get_registers() directly returns the return value of
usb_control_msg_recv() - 0 if successful, and negative error number 
otherwise.
However, in set_ethernet_addr(), this return value is incorrectly 
checked.

Since this return value will never be equal to sizeof(node_id), a 
random MAC address will always be generated and assigned to the 
device; even in cases when get_registers() is successful.

Correctly modifying the condition that checks if get_registers() was 
successful or not fixes this problem, and copies the ethernet address
appropriately.

Fixes: f45a4248ea4c ("set random MAC address when set_ethernet_addr() fails")
Signed-off-by: Anant Thazhemadam <anant.thazhemadam@...il.com>
---
 drivers/net/usb/rtl8150.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/usb/rtl8150.c b/drivers/net/usb/rtl8150.c
index f020401adf04..bf8a60533f3e 100644
--- a/drivers/net/usb/rtl8150.c
+++ b/drivers/net/usb/rtl8150.c
@@ -261,7 +261,7 @@ static void set_ethernet_addr(rtl8150_t *dev)

 	ret = get_registers(dev, IDR, sizeof(node_id), node_id);

-	if (ret == sizeof(node_id)) {
+	if (!ret) {
 		ether_addr_copy(dev->netdev->dev_addr, node_id);
 	} else {
 		eth_hw_addr_random(dev->netdev);
-- 
2.25.1