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Code Issues Releases Wiki Activity

usb: gadget: u_ether: fix race in setting MAC address in setup phase

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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: bcd4a1c40b ("usb: gadget: u_ether: construct with default values and add setters/getters")
Cc: stable@vger.kernel.org
Signed-off-by: Marian Postevca <posteuca@mutex.one>
Link: https://lore.kernel.org/r/20211204214912.17627-1-posteuca@mutex.one
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Marian Postevca 2021-12-04 23:49:12 +02:00 committed by Greg Kroah-Hartman
parent 2585cf9dfa
commit 890d5b4090
1 changed files with 6 additions and 10 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

16
drivers/usb/gadget/function/u_ether.c
View file

@ -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;
}