[PATCHv2 net] usbnet: modern method to get random MAC

From: Oliver Neukum
Date: Thu Aug 29 2024 - 13:52:20 EST


The driver generates a random MAC once on load
and uses it over and over, including on two devices
needing a random MAC at the same time.

Jakub suggested revamping the driver to the modern
API for setting a random MAC rather than fixing
the old stuff.

The bug is as old as the driver.

Signed-off-by: Oliver Neukum <oneukum@xxxxxxxx>

---

v2: Correct commentary style

drivers/net/usb/usbnet.c | 11 +++--------
1 file changed, 3 insertions(+), 8 deletions(-)

diff --git a/drivers/net/usb/usbnet.c b/drivers/net/usb/usbnet.c
index dfc37016690b..40536e1cb4df 100644
--- a/drivers/net/usb/usbnet.c
+++ b/drivers/net/usb/usbnet.c
@@ -61,9 +61,6 @@

/*-------------------------------------------------------------------------*/

-// randomly generated ethernet address
-static u8 node_id [ETH_ALEN];
-
/* use ethtool to change the level for any given device */
static int msg_level = -1;
module_param (msg_level, int, 0);
@@ -1743,7 +1740,6 @@ usbnet_probe (struct usb_interface *udev, const struct usb_device_id *prod)

dev->net = net;
strscpy(net->name, "usb%d", sizeof(net->name));
- eth_hw_addr_set(net, node_id);

/* rx and tx sides can use different message sizes;
* bind() should set rx_urb_size in that case.
@@ -1819,9 +1815,9 @@ usbnet_probe (struct usb_interface *udev, const struct usb_device_id *prod)
goto out4;
}

- /* let userspace know we have a random address */
- if (ether_addr_equal(net->dev_addr, node_id))
- net->addr_assign_type = NET_ADDR_RANDOM;
+ /* this flags the device for user space */
+ if (!is_valid_ether_addr(net->dev_addr))
+ eth_hw_addr_random(net);

if ((dev->driver_info->flags & FLAG_WLAN) != 0)
SET_NETDEV_DEVTYPE(net, &wlan_type);
@@ -2229,7 +2225,6 @@ static int __init usbnet_init(void)
BUILD_BUG_ON(
sizeof_field(struct sk_buff, cb) < sizeof(struct skb_data));

- eth_random_addr(node_id);
return 0;
}
module_init(usbnet_init);
--
2.45.2