Re: KMSAN: uninit-value in alauda_check_media

[syzbot]

Hello,

syzbot has tested the proposed patch but the reproducer still triggered  
crash:
KMSAN: uninit-value in alauda_check_media

=====================================================
BUG: KMSAN: uninit-value in alauda_transport+0x462/0x57f0  
drivers/usb/storage/alauda.c:1138
CPU: 1 PID: 11015 Comm: usb-storage Not tainted 5.4.0-rc2+ #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x191/0x1f0 lib/dump_stack.c:113
 kmsan_report+0x14c/0x2c0 mm/kmsan/kmsan_report.c:110
 __msan_warning+0x73/0xe0 mm/kmsan/kmsan_instr.c:245
 alauda_check_media+0x344/0x3310 drivers/usb/storage/alauda.c:461
 alauda_transport+0x462/0x57f0 drivers/usb/storage/alauda.c:1138
 usb_stor_invoke_transport+0xf5/0x27e0 drivers/usb/storage/transport.c:606
 usb_stor_transparent_scsi_command+0x5d/0x70  
drivers/usb/storage/protocol.c:108
 usb_stor_control_thread+0xca6/0x11a0 drivers/usb/storage/usb.c:380
 kthread+0x4b5/0x4f0 kernel/kthread.c:256
 ret_from_fork+0x35/0x40 arch/x86/entry/entry_64.S:355

Local variable description: ----status@alauda_check_media
Kernel panic - not syncing: panic_on_warn set ...
CPU: 1 PID: 11015 Comm: usb-storage Tainted: G    B             5.4.0-rc2+  
#0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011
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:220
 kmsan_report+0x2b4/0x2c0 mm/kmsan/kmsan_report.c:133
 __msan_warning+0x73/0xe0 mm/kmsan/kmsan_instr.c:245
 alauda_check_media+0x344/0x3310 drivers/usb/storage/alauda.c:461
 alauda_transport+0x462/0x57f0 drivers/usb/storage/alauda.c:1138
 usb_stor_invoke_transport+0xf5/0x27e0 drivers/usb/storage/transport.c:606
 usb_stor_transparent_scsi_command+0x5d/0x70  
drivers/usb/storage/protocol.c:108
 usb_stor_control_thread+0xca6/0x11a0 drivers/usb/storage/usb.c:380
 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..


Tested on:

commit:         c40e5c97 kmsan: drop some dead code in kmsan_shadow.c
git tree:       https://github.com/google/kmsan.git master
console output: https://syzkaller.appspot.com/x/log.txt?x=153ba453600000
kernel config:  https://syzkaller.appspot.com/x/.config?x=49548798e87d32d7
dashboard link: https://syzkaller.appspot.com/bug?extid=e7d46eb426883fb97efd
compiler:       clang version 9.0.0 (/home/glider/llvm/clang  
80fee25776c2fb61e74c1ecb1a523375c2500b69)