From dbecb1cdc06b2349ccd7f2d9fb1c2a5e13327ad9 Mon Sep 17 00:00:00 2001 From: Marian Postevca Date: Sat, 4 Dec 2021 23:49:12 +0200 Subject: [PATCH] usb: gadget: u_ether: fix race in setting MAC address in setup phase 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(). Fixes: 95a5cf8b4900bbb4 ("usb: gadget: u_ether: construct with default values and add setters/getters") Cc: stable@vger.kernel.org Signed-off-by: Marian Postevca Link: https://lore.kernel.org/r/20211204214912.17627-1-posteuca@mutex.one Signed-off-by: Greg Kroah-Hartman --- 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 e0ad5aed6ac98..6f5d45ef2e39a 100644 --- a/drivers/usb/gadget/function/u_ether.c +++ b/drivers/usb/gadget/function/u_ether.c @@ -17,6 +17,7 @@ #include #include #include +#include #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; } -- 2.39.5