KMSAN: uninit-value in dvb_usb_device_exit

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit:    61ccdad1 Revert "drm/bochs: Use shadow buffer for bochs fr..
git tree:       https://github.com/google/kmsan.git master
console output: https://syzkaller.appspot.com/x/log.txt?x=11b7d1ac600000
kernel config:  https://syzkaller.appspot.com/x/.config?x=27abc558ecb16a3b
dashboard link: https://syzkaller.appspot.com/bug?extid=20a83e47e94e371740d2
compiler:       clang version 9.0.0 (/home/glider/llvm/clang  
80fee25776c2fb61e74c1ecb1a523375c2500b69)
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=15aff61e600000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=105a0f22600000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+20a83e47e94e371740d2@xxxxxxxxxxxxxxxxxxxxxxxxx

input: TeVii S632 USB as  
/devices/platform/dummy_hcd.0/usb1/1-1/rc/rc0/input5
dvb-usb: schedule remote query interval to 150 msecs.
dw2102: su3000_power_ctrl: 0, initialized 1
dvb-usb: TeVii S632 USB successfully initialized and connected.
usb 1-1: USB disconnect, device number 2
==================================================================
BUG: KMSAN: uninit-value in strscpy+0x33f/0x4c0 lib/string.c:207
CPU: 0 PID: 3148 Comm: kworker/0:2 Not tainted 5.3.0-rc3+ #17
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+0x162/0x2d0 mm/kmsan/kmsan_report.c:109
 __msan_warning+0x75/0xe0 mm/kmsan/kmsan_instr.c:294
 strscpy+0x33f/0x4c0 lib/string.c:207
 dvb_usb_device_exit+0x1c8/0x270  
drivers/media/usb/dvb-usb/dvb-usb-init.c:305
 dw2102_disconnect+0x256/0x2a0 drivers/media/usb/dvb-usb/dw2102.c:2446
 usb_unbind_interface+0x3a2/0xdd0 drivers/usb/core/driver.c:423
 __device_release_driver drivers/base/dd.c:1120 [inline]
 device_release_driver_internal+0x911/0xd20 drivers/base/dd.c:1151
 device_release_driver+0x4b/0x60 drivers/base/dd.c:1174
 bus_remove_device+0x4bf/0x670 drivers/base/bus.c:556
 device_del+0xcd5/0x1d10 drivers/base/core.c:2288
 usb_disable_device+0x567/0x1150 drivers/usb/core/message.c:1241
 usb_disconnect+0x51e/0xd60 drivers/usb/core/hub.c:2199
 hub_port_connect drivers/usb/core/hub.c:4949 [inline]
 hub_port_connect_change drivers/usb/core/hub.c:5213 [inline]
 port_event drivers/usb/core/hub.c:5359 [inline]
 hub_event+0x3fd0/0x72f0 drivers/usb/core/hub.c:5441
 process_one_work+0x1572/0x1ef0 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:256
 ret_from_fork+0x35/0x40 arch/x86/entry/entry_64.S:355

Uninit was created at:
 kmsan_save_stack_with_flags mm/kmsan/kmsan.c:187 [inline]
 kmsan_internal_poison_shadow+0x53/0xa0 mm/kmsan/kmsan.c:146
 kmsan_slab_free+0x8d/0x100 mm/kmsan/kmsan_hooks.c:195
 slab_free_freelist_hook mm/slub.c:1472 [inline]
 slab_free mm/slub.c:3038 [inline]
 kfree+0x4c1/0x2db0 mm/slub.c:3980
 dw2102_probe+0xbd1/0xce0 drivers/media/usb/dvb-usb/dw2102.c:2387
 usb_probe_interface+0xd19/0x1310 drivers/usb/core/driver.c:361
 really_probe+0x1373/0x1dc0 drivers/base/dd.c:552
 driver_probe_device+0x1ba/0x510 drivers/base/dd.c:709
 __device_attach_driver+0x5b8/0x790 drivers/base/dd.c:816
 bus_for_each_drv+0x28e/0x3b0 drivers/base/bus.c:454
 __device_attach+0x489/0x750 drivers/base/dd.c:882
 device_initial_probe+0x4a/0x60 drivers/base/dd.c:929
 bus_probe_device+0x131/0x390 drivers/base/bus.c:514
 device_add+0x25b5/0x2df0 drivers/base/core.c:2114
 usb_set_configuration+0x309f/0x3710 drivers/usb/core/message.c:2027
 generic_probe+0xe7/0x280 drivers/usb/core/generic.c:210
 usb_probe_device+0x146/0x200 drivers/usb/core/driver.c:266
 really_probe+0x1373/0x1dc0 drivers/base/dd.c:552
 driver_probe_device+0x1ba/0x510 drivers/base/dd.c:709
 __device_attach_driver+0x5b8/0x790 drivers/base/dd.c:816
 bus_for_each_drv+0x28e/0x3b0 drivers/base/bus.c:454
 __device_attach+0x489/0x750 drivers/base/dd.c:882
 device_initial_probe+0x4a/0x60 drivers/base/dd.c:929
 bus_probe_device+0x131/0x390 drivers/base/bus.c:514
 device_add+0x25b5/0x2df0 drivers/base/core.c:2114
 usb_new_device+0x23e5/0x2fb0 drivers/usb/core/hub.c:2536
 hub_port_connect drivers/usb/core/hub.c:5098 [inline]
 hub_port_connect_change drivers/usb/core/hub.c:5213 [inline]
 port_event drivers/usb/core/hub.c:5359 [inline]
 hub_event+0x581d/0x72f0 drivers/usb/core/hub.c:5441
 process_one_work+0x1572/0x1ef0 kernel/workqueue.c:2269
 worker_thread+0x111b/0x2460 kernel/workqueue.c:2415
 kthread+0x4b5/0x4f0 kernel/kthread.c:256
 ret_from_fork+0x35/0x40 arch/x86/entry/entry_64.S:355
==================================================================


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