When listening for notifications through netlink of a new interface being registered, sporadically, it is possible for the MAC to be read as zero. The zero MAC address lasts a short period of time and then switches to a valid random MAC address.

This causes problems for netd in Android, which assumes that the interface is malfunctioning and will not use it.

In the good case we get this log: InterfaceController::getCfg() ifName usb0 hwAddr 92:a8:f0:73:79:5b ipv4Addr 0.0.0.0 flags 0x1002

In the error case we get these logs: InterfaceController::getCfg() ifName usb0 hwAddr 00:00:00:00:00:00 ipv4Addr 0.0.0.0 flags 0x1002

netd : interfaceGetCfg("usb0") netd : interfaceSetCfg() -> ServiceSpecificException (99, "[Cannot assign requested address] : ioctl() failed")

The reason for the issue is the order in which the interface is setup, it is first registered through register_netdev() and after the MAC address is set.

Fixed by first setting the MAC address of the net_device and after that calling register_netdev().

Signed-off-by: Marian Postevca posteuca@mutex.one Fixes: bcd4a1c40bee885e ("usb: gadget: u_ether: construct with default values and add setters/getters") Cc: stable@vger.kernel.org ---

v2: Added Fixes and Cc tags to commit message.

drivers/usb/gadget/function/u_ether.c | 16 ++++++---------- 1 file changed, 6 insertions(+), 10 deletions(-)

diff --git a/drivers/usb/gadget/function/u_ether.c b/drivers/usb/gadget/function/u_ether.c index e0ad5aed6ac9..6f5d45ef2e39 100644 --- a/drivers/usb/gadget/function/u_ether.c +++ b/drivers/usb/gadget/function/u_ether.c @@ -17,6 +17,7 @@ #include <linux/etherdevice.h> #include <linux/ethtool.h> #include <linux/if_vlan.h> +#include <linux/etherdevice.h>

#include "u_ether.h"

@@ -863,19 +864,23 @@ int gether_register_netdev(struct net_device *net) { struct eth_dev *dev; struct usb_gadget *g; - struct sockaddr sa; int status;

if (!net->dev.parent) return -EINVAL; dev = netdev_priv(net); g = dev->gadget; + + net->addr_assign_type = NET_ADDR_RANDOM; + eth_hw_addr_set(net, dev->dev_mac); + status = register_netdev(net); if (status < 0) { dev_dbg(&g->dev, "register_netdev failed, %d\n", status); return status; } else { INFO(dev, "HOST MAC %pM\n", dev->host_mac); + INFO(dev, "MAC %pM\n", dev->dev_mac);

/* two kinds of host-initiated state changes: * - iff DATA transfer is active, carrier is "on" @@ -883,15 +888,6 @@ int gether_register_netdev(struct net_device *net) */ netif_carrier_off(net); } - sa.sa_family = net->type; - memcpy(sa.sa_data, dev->dev_mac, ETH_ALEN); - rtnl_lock(); - status = dev_set_mac_address(net, &sa, NULL); - rtnl_unlock(); - if (status) - pr_warn("cannot set self ethernet address: %d\n", status); - else - INFO(dev, "MAC %pM\n", dev->dev_mac);

return status; }