KMSAN: uninit-value in tipc_subscrb_rcv_cb

Hello,

syzbot hit the following crash on  
https://github.com/google/kmsan.git/master commit
e2ab7e8abba47a2f2698216258e5d8727ae58717 (Fri Apr 6 16:24:31 2018 +0000)
kmsan: temporarily disable visitAsmInstruction() to help syzbot
syzbot dashboard link:  
https://syzkaller.appspot.com/bug?extid=75e6e042c5bbf691fc82

Unfortunately, I don't have any reproducer for this crash yet.
Raw console output:  
https://syzkaller.appspot.com/x/log.txt?id=5784467448791040
Kernel config:  
https://syzkaller.appspot.com/x/.config?id=6627248707860932248
compiler: clang version 7.0.0 (trunk 329060) (llvm/trunk 329054)

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+75e6e042c5bbf691fc82@syzkaller.appspotmail.com
It will help syzbot understand when the bug is fixed. See footer for  
details.
If you forward the report, please keep this part and the footer.

==================================================================
BUG: KMSAN: uninit-value in htohl net/tipc/subscr.c:66 [inline]
BUG: KMSAN: uninit-value in tipc_subscrb_rcv_cb+0x418/0xe80  
net/tipc/subscr.c:339
CPU: 1 PID: 5017 Comm: kworker/u4:6 Not tainted 4.16.0+ #81
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011
Workqueue: tipc_rcv tipc_recv_work
Call Trace:
  __dump_stack lib/dump_stack.c:17 [inline]
  dump_stack+0x185/0x1d0 lib/dump_stack.c:53
  kmsan_report+0x142/0x240 mm/kmsan/kmsan.c:1067
  __msan_warning_32+0x6c/0xb0 mm/kmsan/kmsan_instr.c:676
  htohl net/tipc/subscr.c:66 [inline]
  tipc_subscrb_rcv_cb+0x418/0xe80 net/tipc/subscr.c:339
  tipc_receive_from_sock+0x64c/0x800 net/tipc/server.c:271
  tipc_recv_work+0xd8/0x1f0 net/tipc/server.c:618
  process_one_work+0x12c6/0x1f60 kernel/workqueue.c:2113
  worker_thread+0x113c/0x24f0 kernel/workqueue.c:2247
  kthread+0x539/0x720 kernel/kthread.c:239
  ret_from_fork+0x35/0x40 arch/x86/entry/entry_64.S:406

Uninit was created at:
  kmsan_save_stack_with_flags mm/kmsan/kmsan.c:278 [inline]
  kmsan_internal_poison_shadow+0xb8/0x1b0 mm/kmsan/kmsan.c:188
  kmsan_kmalloc+0x94/0x100 mm/kmsan/kmsan.c:314
  kmem_cache_alloc+0xaab/0xb90 mm/slub.c:2756
  tipc_receive_from_sock+0x15c/0x800 net/tipc/server.c:253
  tipc_recv_work+0xd8/0x1f0 net/tipc/server.c:618
  process_one_work+0x12c6/0x1f60 kernel/workqueue.c:2113
  worker_thread+0x113c/0x24f0 kernel/workqueue.c:2247
  kthread+0x539/0x720 kernel/kthread.c:239
  ret_from_fork+0x35/0x40 arch/x86/entry/entry_64.S:406
==================================================================
Kernel panic - not syncing: panic_on_warn set ...

CPU: 1 PID: 5017 Comm: kworker/u4:6 Tainted: G    B            4.16.0+ #81
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011
Workqueue: tipc_rcv tipc_recv_work
Call Trace:
  __dump_stack lib/dump_stack.c:17 [inline]
  dump_stack+0x185/0x1d0 lib/dump_stack.c:53
  panic+0x39d/0x940 kernel/panic.c:183
  kmsan_report+0x238/0x240 mm/kmsan/kmsan.c:1083
  __msan_warning_32+0x6c/0xb0 mm/kmsan/kmsan_instr.c:676
  htohl net/tipc/subscr.c:66 [inline]
  tipc_subscrb_rcv_cb+0x418/0xe80 net/tipc/subscr.c:339
  tipc_receive_from_sock+0x64c/0x800 net/tipc/server.c:271
  tipc_recv_work+0xd8/0x1f0 net/tipc/server.c:618
  process_one_work+0x12c6/0x1f60 kernel/workqueue.c:2113
  worker_thread+0x113c/0x24f0 kernel/workqueue.c:2247
  kthread+0x539/0x720 kernel/kthread.c:239
  ret_from_fork+0x35/0x40 arch/x86/entry/entry_64.S:406
Shutting down cpus with NMI
Dumping ftrace buffer:
    (ftrace buffer empty)
Kernel Offset: disabled
Rebooting in 86400 seconds..


---
This bug is generated by a dumb bot. It may contain errors.
See https://goo.gl/tpsmEJ for details.
Direct all questions to syzkaller@googlegroups.com.

syzbot will keep track of this bug report.
If you forgot to add the Reported-by tag, once the fix for this bug is  
merged
into any tree, please reply to this email with:
#syz fix: exact-commit-title
To mark this as a duplicate of another syzbot report, please reply with:
#syz dup: exact-subject-of-another-report
If it's a one-off invalid bug report, please reply with:
#syz invalid
Note: if the crash happens again, it will cause creation of a new bug  
report.
Note: all commands must start from beginning of the line in the email body.