KMSAN: uninit-value in tomoyo_check_unix_address

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit:    3b955a40 usb-fuzzer: main usb gadget fuzzer driver
git tree:       kmsan
console output: https://syzkaller.appspot.com/x/log.txt?x=15014d44a00000
kernel config:  https://syzkaller.appspot.com/x/.config?x=602468164ccdc30a
dashboard link: https://syzkaller.appspot.com/bug?extid=e9687dbb0b6b2057d0ed
compiler:       clang version 9.0.0 (/home/glider/llvm/clang  
06d00afa61eef8f7f501ebdb4e8612ea43ec2d78)

Unfortunately, I don't have any reproducer for this crash yet.

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+e9687dbb0b6b2057d0ed at syzkaller.appspotmail.com

==================================================================
BUG: KMSAN: uninit-value in tomoyo_check_unix_address+0x36a/0xa30  
security/tomoyo/network.c:597
CPU: 1 PID: 30810 Comm: syz-executor.4 Not tainted 5.1.0+ #3
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+0x130/0x2a0 mm/kmsan/kmsan.c:619
  __msan_warning+0x75/0xe0 mm/kmsan/kmsan_instr.c:310
  tomoyo_check_unix_address+0x36a/0xa30 security/tomoyo/network.c:597
  tomoyo_socket_connect_permission+0x315/0x400 security/tomoyo/network.c:705
  tomoyo_socket_connect+0x8b/0xa0 security/tomoyo/tomoyo.c:456
  security_socket_connect+0x127/0x200 security/security.c:1948
  __sys_connect+0x536/0x820 net/socket.c:1804
  __do_sys_connect net/socket.c:1819 [inline]
  __se_sys_connect+0x8d/0xb0 net/socket.c:1816
  __x64_sys_connect+0x4a/0x70 net/socket.c:1816
  do_syscall_64+0xbc/0xf0 arch/x86/entry/common.c:291
  entry_SYSCALL_64_after_hwframe+0x63/0xe7
RIP: 0033:0x458da9
Code: ad b8 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7  
48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff  
ff 0f 83 7b b8 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f825eeb8c78 EFLAGS: 00000246 ORIG_RAX: 000000000000002a
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000458da9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000003
RBP: 000000000073bf00 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f825eeb96d4
R13: 00000000004bf2cf R14: 00000000004d0660 R15: 00000000ffffffff

Local variable description: ----address at __sys_connect
Variable was created at:
  sockfd_lookup_light net/socket.c:488 [inline]
  __sys_connect+0x8c/0x820 net/socket.c:1796
  __do_sys_connect net/socket.c:1819 [inline]
  __se_sys_connect+0x8d/0xb0 net/socket.c:1816
==================================================================


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