KMSAN: uninit-value in digitv_rc_query

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit:    1e76a3e5 kmsan: replace __GFP_NO_KMSAN_SHADOW with kmsan_i..
git tree:       https://github.com/google/kmsan.git master
console output: https://syzkaller.appspot.com/x/log.txt?x=16860a63600000
kernel config:  https://syzkaller.appspot.com/x/.config?x=f03c659d0830ab8d
dashboard link: https://syzkaller.appspot.com/bug?extid=6bf9606ee955b646c0e1
compiler:       clang version 9.0.0 (/home/glider/llvm/clang  
80fee25776c2fb61e74c1ecb1a523375c2500b69)
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=12c1101b600000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=15db3cfd600000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+6bf9606ee955b646c0e1@xxxxxxxxxxxxxxxxxxxxxxxxx

dvb-usb: schedule remote query interval to 1000 msecs.
dvb-usb: Nebula Electronics uDigiTV DVB-T USB2.0) successfully initialized  
and connected.
dvb-usb: bulk message failed: -22 (7/0)
dvb-usb: bulk message failed: -22 (7/0)
dvb-usb: bulk message failed: -22 (7/-30591)
dvb-usb: bulk message failed: -22 (7/0)
=====================================================
BUG: KMSAN: uninit-value in legacy_dvb_usb_read_remote_control+0x106/0x790  
drivers/media/usb/dvb-usb/dvb-usb-remote.c:123
CPU: 1 PID: 3844 Comm: kworker/1:2 Not tainted 5.3.0-rc7+ #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011
Workqueue: events legacy_dvb_usb_read_remote_control
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x191/0x1f0 lib/dump_stack.c:113
 kmsan_report+0x13a/0x2b0 mm/kmsan/kmsan_report.c:108
 __msan_warning+0x73/0xe0 mm/kmsan/kmsan_instr.c:250
 digitv_rc_query+0x76a/0x890 drivers/media/usb/dvb-usb/digitv.c:259
 legacy_dvb_usb_read_remote_control+0x106/0x790  
drivers/media/usb/dvb-usb/dvb-usb-remote.c:123
 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

Local variable description: ----key@digitv_rc_query
Variable was created at:
 digitv_rc_query+0x78/0x890 drivers/media/usb/dvb-usb/digitv.c:234
 legacy_dvb_usb_read_remote_control+0x106/0x790  
drivers/media/usb/dvb-usb/dvb-usb-remote.c:123
=====================================================
Kernel panic - not syncing: panic_on_warn set ...
CPU: 1 PID: 3844 Comm: kworker/1:2 Tainted: G    B             5.3.0-rc7+ #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011
Workqueue: events legacy_dvb_usb_read_remote_control
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x191/0x1f0 lib/dump_stack.c:113
 panic+0x3c9/0xc1e kernel/panic.c:219
 kmsan_report+0x2a2/0x2b0 mm/kmsan/kmsan_report.c:131
 __msan_warning+0x73/0xe0 mm/kmsan/kmsan_instr.c:250
 digitv_rc_query+0x76a/0x890 drivers/media/usb/dvb-usb/digitv.c:259
 legacy_dvb_usb_read_remote_control+0x106/0x790  
drivers/media/usb/dvb-usb/dvb-usb-remote.c:123
 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
Kernel Offset: disabled
Rebooting in 86400 seconds..


---
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