Re: KMSAN: uninit-value in tipc_subscrb_rcv_cb

From: syzbot
Date: Wed Apr 11 2018 - 01:47:08 EST

syzbot has found reproducer for the following crash on https://github.com/google/kmsan.git/master commit
35ff515e4bda2646f6c881d33951c306ea9c282a (Tue Apr 10 08:59:43 2018 +0000)
Merge pull request #11 from parkerduckworth/readme
syzbot dashboard link: https://syzkaller.appspot.com/bug?extid=75e6e042c5bbf691fc82

So far this crash happened 3 times on https://github.com/google/kmsan.git/master.
C reproducer: https://syzkaller.appspot.com/x/repro.c?id=6676653019234304
syzkaller reproducer: https://syzkaller.appspot.com/x/repro.syz?id=5693411524870144
Raw console output: https://syzkaller.appspot.com/x/log.txt?id=5043527943716864
Kernel config: https://syzkaller.appspot.com/x/.config?id=6627248707860932248
compiler: clang version 7.0.0 (trunk 329391)

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+75e6e042c5bbf691fc82@xxxxxxxxxxxxxxxxxxxxxxxxx
It will help syzbot understand when the bug is fixed.

==================================================================
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: 0 PID: 19 Comm: kworker/u4:1 Not tainted 4.16.0+ #83
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
==================================================================