Subject: Re: [syzbot] KMSAN: uninit-value in ax88179_led_setting

From: syzbot <[email-masked]>
Date: Wed, 06 Apr 2022 19:41:21 -0700

syzbot has found a reproducer for the following issue on:

HEAD commit:    33d9269ef6e0 Revert "kernel: kmsan: don't instrument stack..
git tree:       https://github.com/google/kmsan.git master
console output: https://syzkaller.appspot.com/x/log.txt?x=158ddbcf700000
kernel config:  https://syzkaller.appspot.com/x/.config?x=d830111cc3be873
dashboard link: https://syzkaller.appspot.com/bug?extid=d3dbdf31fbe9d8f5f311
compiler:       clang version 14.0.0 (/usr/local/google/src/llvm-git-monorepo 2b554920f11c8b763cd9ed9003f4e19b919b8e1f), GNU ld (GNU Binutils for Debian) 2.35.2
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=146e3dc3700000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: [email-masked]

ax88179_178a 2-1:0.252 (unnamed net_device) (uninitialized): Failed to read reg index 0x0001: -71
ax88179_178a 2-1:0.252 (unnamed net_device) (uninitialized): Failed to read reg index 0x0002: -71
=====================================================
BUG: KMSAN: uninit-value in ax88179_check_eeprom drivers/net/usb/ax88179_178a.c:1074 [inline]
BUG: KMSAN: uninit-value in ax88179_led_setting+0x884/0x30b0 drivers/net/usb/ax88179_178a.c:1168
 ax88179_check_eeprom drivers/net/usb/ax88179_178a.c:1074 [inline]
 ax88179_led_setting+0x884/0x30b0 drivers/net/usb/ax88179_178a.c:1168
 ax88179_bind+0xf00/0x1a50 drivers/net/usb/ax88179_178a.c:1412
 usbnet_probe+0x1251/0x4160 drivers/net/usb/usbnet.c:1747
 usb_probe_interface+0xf19/0x1600 drivers/usb/core/driver.c:396
 really_probe+0x653/0x14b0 drivers/base/dd.c:596
 __driver_probe_device+0x3e9/0x530 drivers/base/dd.c:755
 driver_probe_device drivers/base/dd.c:785 [inline]
 __device_attach_driver+0x79f/0x1120 drivers/base/dd.c:902
 bus_for_each_drv+0x2d6/0x3f0 drivers/base/bus.c:427
 __device_attach+0x593/0x8e0 drivers/base/dd.c:973
 device_initial_probe+0x4a/0x60 drivers/base/dd.c:1020
 bus_probe_device+0x17b/0x3e0 drivers/base/bus.c:487
 device_add+0x1fff/0x26e0 drivers/base/core.c:3405
 usb_set_configuration+0x37e9/0x3ed0 drivers/usb/core/message.c:2170
 usb_generic_driver_probe+0x13c/0x300 drivers/usb/core/generic.c:238
 usb_probe_device+0x309/0x570 drivers/usb/core/driver.c:293
 really_probe+0x653/0x14b0 drivers/base/dd.c:596
 __driver_probe_device+0x3e9/0x530 drivers/base/dd.c:755
 driver_probe_device drivers/base/dd.c:785 [inline]
 __device_attach_driver+0x79f/0x1120 drivers/base/dd.c:902
 bus_for_each_drv+0x2d6/0x3f0 drivers/base/bus.c:427
 __device_attach+0x593/0x8e0 drivers/base/dd.c:973
 device_initial_probe+0x4a/0x60 drivers/base/dd.c:1020
 bus_probe_device+0x17b/0x3e0 drivers/base/bus.c:487
 device_add+0x1fff/0x26e0 drivers/base/core.c:3405
 usb_new_device+0x1b8e/0x2950 drivers/usb/core/hub.c:2566
 hub_port_connect drivers/usb/core/hub.c:5358 [inline]
 hub_port_connect_change drivers/usb/core/hub.c:5502 [inline]
 port_event drivers/usb/core/hub.c:5660 [inline]
 hub_event+0x58e3/0x89e0 drivers/usb/core/hub.c:5742
 process_one_work+0xdb6/0x1820 kernel/workqueue.c:2307
 worker_thread+0x10b3/0x21e0 kernel/workqueue.c:2454
 kthread+0x3c7/0x500 kernel/kthread.c:377
 ret_from_fork+0x1f/0x30

Local variable eeprom.i created at:
 ax88179_check_eeprom drivers/net/usb/ax88179_178a.c:1045 [inline]
 ax88179_led_setting+0x2e2/0x30b0 drivers/net/usb/ax88179_178a.c:1168
 ax88179_bind+0xf00/0x1a50 drivers/net/usb/ax88179_178a.c:1412

CPU: 0 PID: 7 Comm: kworker/0:1 Not tainted 5.17.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: usb_hub_wq hub_event
=====================================================