[PATCH net-next] tipc: eliminate complaint of KMSAN uninit-value in tipc_conn_rcv_sub

[Ying Xue <ying.xue@windriver.com>]

As variable s of struct tipc_subscr type is not initialized
in tipc_conn_rcv_from_sock() before it is used in tipc_conn_rcv_sub(),
KMSAN reported the following uninit-value type complaint:

==================================================================
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+
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..

Reported-by: syzbot+8951a3065ee7fd6d6e23@syzkaller.appspotmail.com
Signed-off-by: Ying Xue <ying.xue@windriver.com>
---
 net/tipc/topsrv.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/net/tipc/topsrv.c b/net/tipc/topsrv.c
index c8e34ef..fe47a62 100644
--- a/net/tipc/topsrv.c
+++ b/net/tipc/topsrv.c
@@ -397,6 +397,7 @@ static int tipc_conn_rcv_from_sock(struct tipc_conn *con)
 	struct kvec iov;
 	int ret;
 
+	memset(&s, 0, sizeof(s));
 	iov.iov_base = &s;
 	iov.iov_len = sizeof(s);
 	msg.msg_name = NULL;
-- 
2.7.4


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