net: usb: asix: init MAC address buffers

This is for fixing bug KMSAN: uninit-value in ax88772_bind

Tested by
https://groups.google.com/d/msg/syzkaller-bugs/aFQurGotng4/eB_HlNhhCwAJ

Reported-by: syzbot+8a3fc6674bbc3978ed4e@syzkaller.appspotmail.com

syzbot found the following crash on:

HEAD commit:    f75e4cfe kmsan: use kmsan_handle_urb() in urb.c
git tree:       kmsan
console output: https://syzkaller.appspot.com/x/log.txt?x=136d720ea00000
kernel config:
https://syzkaller.appspot.com/x/.config?x=602468164ccdc30a
dashboard link:
https://syzkaller.appspot.com/bug?extid=8a3fc6674bbc3978ed4e
compiler:       clang version 9.0.0 (/home/glider/llvm/clang
06d00afa61eef8f7f501ebdb4e8612ea43ec2d78)
syz repro:
https://syzkaller.appspot.com/x/repro.syz?x=12788316a00000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=120359aaa00000

==================================================================
BUG: KMSAN: uninit-value in is_valid_ether_addr
include/linux/etherdevice.h:200 [inline]
BUG: KMSAN: uninit-value in asix_set_netdev_dev_addr
drivers/net/usb/asix_devices.c:73 [inline]
BUG: KMSAN: uninit-value in ax88772_bind+0x93d/0x11e0
drivers/net/usb/asix_devices.c:724
CPU: 0 PID: 3348 Comm: kworker/0:2 Not tainted 5.1.0+ #1
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
Workqueue: usb_hub_wq hub_event
Call Trace:
  __dump_stack lib/dump_stack.c:77 [inline]
  dump_stack+0x191/0x1f0 lib/dump_stack.c:113
  kmsan_report+0x130/0x2a0 mm/kmsan/kmsan.c:622
  __msan_warning+0x75/0xe0 mm/kmsan/kmsan_instr.c:310
  is_valid_ether_addr include/linux/etherdevice.h:200 [inline]
  asix_set_netdev_dev_addr drivers/net/usb/asix_devices.c:73 [inline]
  ax88772_bind+0x93d/0x11e0 drivers/net/usb/asix_devices.c:724
  usbnet_probe+0x10f5/0x3940 drivers/net/usb/usbnet.c:1728
  usb_probe_interface+0xd66/0x1320 drivers/usb/core/driver.c:361
  really_probe+0xdae/0x1d80 drivers/base/dd.c:513
  driver_probe_device+0x1b3/0x4f0 drivers/base/dd.c:671
  __device_attach_driver+0x5b8/0x790 drivers/base/dd.c:778
  bus_for_each_drv+0x28e/0x3b0 drivers/base/bus.c:454
  __device_attach+0x454/0x730 drivers/base/dd.c:844
  device_initial_probe+0x4a/0x60 drivers/base/dd.c:891
  bus_probe_device+0x137/0x390 drivers/base/bus.c:514
  device_add+0x288d/0x30e0 drivers/base/core.c:2106
  usb_set_configuration+0x30dc/0x3750 drivers/usb/core/message.c:2027
  generic_probe+0xe7/0x280 drivers/usb/core/generic.c:210
  usb_probe_device+0x14c/0x200 drivers/usb/core/driver.c:266
  really_probe+0xdae/0x1d80 drivers/base/dd.c:513
  driver_probe_device+0x1b3/0x4f0 drivers/base/dd.c:671
  __device_attach_driver+0x5b8/0x790 drivers/base/dd.c:778
  bus_for_each_drv+0x28e/0x3b0 drivers/base/bus.c:454
  __device_attach+0x454/0x730 drivers/base/dd.c:844
  device_initial_probe+0x4a/0x60 drivers/base/dd.c:891
  bus_probe_device+0x137/0x390 drivers/base/bus.c:514
  device_add+0x288d/0x30e0 drivers/base/core.c:2106
  usb_new_device+0x23e5/0x2ff0 drivers/usb/core/hub.c:2534
  hub_port_connect drivers/usb/core/hub.c:5089 [inline]
  hub_port_connect_change drivers/usb/core/hub.c:5204 [inline]
  port_event drivers/usb/core/hub.c:5350 [inline]
  hub_event+0x48d1/0x7290 drivers/usb/core/hub.c:5432
  process_one_work+0x1572/0x1f00 kernel/workqueue.c:2269
  process_scheduled_works kernel/workqueue.c:2331 [inline]
  worker_thread+0x189c/0x2460 kernel/workqueue.c:2417
  kthread+0x4b5/0x4f0 kernel/kthread.c:254
  ret_from_fork+0x35/0x40 arch/x86/entry/entry_64.S:355
Signed-off-by: Phong Tran <tranmanphong@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/usb/asix_devices.c

@@ -226,7 +226,7 @@ static void asix_phy_reset(struct usbnet *dev, unsigned int reset_bits)
 static int ax88172_bind(struct usbnet *dev, struct usb_interface *intf)
 {
 	int ret = 0;
-	u8 buf[ETH_ALEN];
+	u8 buf[ETH_ALEN] = {0};
 	int i;
 	unsigned long gpio_bits = dev->driver_info->data;
 
@@ -677,7 +677,7 @@ static int asix_resume(struct usb_interface *intf)
 static int ax88772_bind(struct usbnet *dev, struct usb_interface *intf)
 {
 	int ret, i;
-	u8 buf[ETH_ALEN], chipcode = 0;
+	u8 buf[ETH_ALEN] = {0}, chipcode = 0;
 	u32 phyid;
 	struct asix_common_private *priv;
 
@@ -1061,7 +1061,7 @@ static const struct net_device_ops ax88178_netdev_ops = {
 static int ax88178_bind(struct usbnet *dev, struct usb_interface *intf)
 {
 	int ret;
-	u8 buf[ETH_ALEN];
+	u8 buf[ETH_ALEN] = {0};
 
 	usbnet_get_endpoints(dev,intf);