KMSAN: uninit-value in tipc_conn_rcv_sub

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: 74ee2200b89f kmsan: bump .config.example to v4.17-rc3
git tree: https://github.com/google/kmsan.git/master
console output: https://syzkaller.appspot.com/x/log.txt?x=12ab8637800000
kernel config: https://syzkaller.appspot.com/x/.config?x=4ca1e57bafa8ab1f
dashboard link: https://syzkaller.appspot.com/bug?extid=8951a3065ee7fd6d6e23
compiler: clang version 7.0.0 (trunk 329391)
syzkaller repro:https://syzkaller.appspot.com/x/repro.syz?x=15a497f7800000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=177c1907800000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+8951a3...@syzkaller.appspotmail.com

random: sshd: uninitialized urandom read (32 bytes read)
random: sshd: uninitialized urandom read (32 bytes read)
random: sshd: uninitialized urandom read (32 bytes read)
random: sshd: uninitialized urandom read (32 bytes read)
==================================================================
BUG: KMSAN: uninit-value in tipc_conn_rcv_sub+0x184/0x950
net/tipc/topsrv.c:373
CPU: 0 PID: 66 Comm: kworker/u4:4 Not tainted 4.17.0-rc3+ #88
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
Workqueue: tipc_rcv tipc_conn_recv_work
Call Trace:
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0x185/0x1d0 lib/dump_stack.c:113
kmsan_report+0x142/0x240 mm/kmsan/kmsan.c:1067
__msan_warning_32+0x6c/0xb0 mm/kmsan/kmsan_instr.c:683
tipc_conn_rcv_sub+0x184/0x950 net/tipc/topsrv.c:373
tipc_conn_rcv_from_sock net/tipc/topsrv.c:409 [inline]
tipc_conn_recv_work+0x3cd/0x560 net/tipc/topsrv.c:424
process_one_work+0x12c6/0x1f60 kernel/workqueue.c:2145
worker_thread+0x113c/0x24f0 kernel/workqueue.c:2279
kthread+0x539/0x720 kernel/kthread.c:239
ret_from_fork+0x35/0x40 arch/x86/entry/entry_64.S:412

Local variable description: ----s.i@tipc_conn_recv_work
Variable was created at:
tipc_conn_recv_work+0x65/0x560 net/tipc/topsrv.c:419
process_one_work+0x12c6/0x1f60 kernel/workqueue.c:2145
==================================================================
Kernel panic - not syncing: panic_on_warn set ...

CPU: 0 PID: 66 Comm: kworker/u4:4 Tainted: G B 4.17.0-rc3+
#88
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
Workqueue: tipc_rcv tipc_conn_recv_work
Call Trace:
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0x185/0x1d0 lib/dump_stack.c:113
panic+0x39d/0x940 kernel/panic.c:184
kmsan_report+0x238/0x240 mm/kmsan/kmsan.c:1083
__msan_warning_32+0x6c/0xb0 mm/kmsan/kmsan_instr.c:683
tipc_conn_rcv_sub+0x184/0x950 net/tipc/topsrv.c:373
tipc_conn_rcv_from_sock net/tipc/topsrv.c:409 [inline]
tipc_conn_recv_work+0x3cd/0x560 net/tipc/topsrv.c:424
process_one_work+0x12c6/0x1f60 kernel/workqueue.c:2145
worker_thread+0x113c/0x24f0 kernel/workqueue.c:2279
kthread+0x539/0x720 kernel/kthread.c:239
ret_from_fork+0x35/0x40 arch/x86/entry/entry_64.S:412
Dumping ftrace buffer:
(ftrace buffer empty)
Kernel Offset: disabled
Rebooting in 86400 seconds..


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