KMSAN: uninit-value in r871xu_drv_init

[syzbot]

Hello,

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=153453dea00000
kernel config:  https://syzkaller.appspot.com/x/.config?x=602468164ccdc30a
dashboard link: https://syzkaller.appspot.com/bug?extid=6f5ecd144854c0d8580b
compiler:       clang version 9.0.0 (/home/glider/llvm/clang  
06d00afa61eef8f7f501ebdb4e8612ea43ec2d78)
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=161892c1a00000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=11b20986a00000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+6f5ecd144854c0d8580b@xxxxxxxxxxxxxxxxxxxxxxxxx

usb 1-1: config 0 has no interface number 0
usb 1-1: New USB device found, idVendor=050d, idProduct=945a,  
bcdDevice=f1.a1
usb 1-1: New USB device strings: Mfr=0, Product=0, SerialNumber=0
usb 1-1: config 0 descriptor??
r8712u: register rtl8712_netdev_ops to netdev_ops
usb 1-1: r8712u: USB_SPEED_LOW with 0 endpoints
usb 1-1: r8712u: Boot from EFUSE: Autoload Failed
==================================================================
BUG: KMSAN: uninit-value in r871xu_drv_init+0x17c6/0x2ad0  
drivers/staging/rtl8712/usb_intf.c:409
CPU: 1 PID: 17 Comm: kworker/1:0 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
 r871xu_drv_init+0x17c6/0x2ad0 drivers/staging/rtl8712/usb_intf.c:409
 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
 worker_thread+0x111b/0x2460 kernel/workqueue.c:2415
 kthread+0x4b5/0x4f0 kernel/kthread.c:254
 ret_from_fork+0x35/0x40 arch/x86/entry/entry_64.S:355

Local variable description: ----data@usb_read8
Variable was created at:
 usb_read8+0x5d/0x130 drivers/staging/rtl8712/usb_ops.c:33
 r8712_read8+0xaa/0xd0 drivers/staging/rtl8712/rtl8712_io.c:29
==================================================================


---
This bug is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzkaller@xxxxxxxxxxxxxxxxx

syzbot will keep track of this bug report. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
syzbot can test patches for this bug, for details see:
https://goo.gl/tpsmEJ#testing-patches