net: usb: asix: init MAC address buffers [Linux 4.9.187]

This Linux kernel change "net: usb: asix: init MAC address buffers" is included in the Linux 4.9.187 release. This change is authored by Phong Tran <tranmanphong [at] gmail.com> on Tue Jul 2 07:10:08 2019 +0700. The commit for this change in Linux stable tree is 9f561a7 (patch) which is from upstream commit 78226f6. The same Linux upstream change may have been applied to various maintained Linux releases and you can find all Linux releases containing changes from upstream 78226f6.

net: usb: asix: init MAC address buffers

[ Upstream commit 78226f6eaac80bf30256a33a4926c194ceefdf36 ]

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: [email protected]

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 <[email protected]>
Signed-off-by: David S. Miller <[email protected]>
Signed-off-by: Sasha Levin <[email protected]>

There are 6 lines of Linux source code added/deleted in this change. Code changes to Linux kernel are as follows.

 drivers/net/usb/asix_devices.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/net/usb/asix_devices.c b/drivers/net/usb/asix_devices.c
index 393fd3e..4b12b6d 100644
--- a/drivers/net/usb/asix_devices.c
+++ b/drivers/net/usb/asix_devices.c
@@ -237,7 +237,7 @@ 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;

@@ -687,7 +687,7 @@ 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;

@@ -1064,7 +1064,7 @@ static int ax88178_change_mtu(struct net_device *net, int new_mtu)
 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);

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