[PATCH net] tipc: fix one byte leak in tipc_sk_set_orig_addr()

[Eric Dumazet <edumazet@google.com>]

sysbot/KMSAN reported an uninit-value in recvmsg() that
I tracked down to tipc_sk_set_orig_addr(), missing
srcaddr->member.scope initialization.

This patches moves srcaddr->sock.scope init to follow
fields order and ease future verifications.

BUG: KMSAN: uninit-value in copy_to_user include/linux/uaccess.h:184 [inline]
BUG: KMSAN: uninit-value in move_addr_to_user+0x32e/0x530 net/socket.c:226
CPU: 0 PID: 4549 Comm: syz-executor287 Not tainted 4.17.0-rc3+ #88
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+0x185/0x1d0 lib/dump_stack.c:113
 kmsan_report+0x142/0x240 mm/kmsan/kmsan.c:1067
 kmsan_internal_check_memory+0x135/0x1e0 mm/kmsan/kmsan.c:1157
 kmsan_copy_to_user+0x69/0x160 mm/kmsan/kmsan.c:1199
 copy_to_user include/linux/uaccess.h:184 [inline]
 move_addr_to_user+0x32e/0x530 net/socket.c:226
 ___sys_recvmsg+0x4e2/0x810 net/socket.c:2285
 __sys_recvmsg net/socket.c:2328 [inline]
 __do_sys_recvmsg net/socket.c:2338 [inline]
 __se_sys_recvmsg net/socket.c:2335 [inline]
 __x64_sys_recvmsg+0x325/0x460 net/socket.c:2335
 do_syscall_64+0x154/0x220 arch/x86/entry/common.c:287
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x4455e9
RSP: 002b:00007fe3bd36ddb8 EFLAGS: 00000246 ORIG_RAX: 000000000000002f
RAX: ffffffffffffffda RBX: 00000000006dac24 RCX: 00000000004455e9
RDX: 0000000000002002 RSI: 0000000020000400 RDI: 0000000000000003
RBP: 00000000006dac20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fff98ce4b6f R14: 00007fe3bd36e9c0 R15: 0000000000000003

Local variable description: ----addr@___sys_recvmsg
Variable was created at:
 ___sys_recvmsg+0xd5/0x810 net/socket.c:2246
 __sys_recvmsg net/socket.c:2328 [inline]
 __do_sys_recvmsg net/socket.c:2338 [inline]
 __se_sys_recvmsg net/socket.c:2335 [inline]
 __x64_sys_recvmsg+0x325/0x460 net/socket.c:2335

Byte 19 of 32 is uninitialized

Fixes: 31c82a2d9d51 ("tipc: add second source address to recvmsg()/recvfrom()")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: syzbot <syzkaller@googlegroups.com>
Cc: Jon Maloy <jon.maloy@ericsson.com>
Cc: Ying Xue <ying.xue@windriver.com>
---
 net/tipc/socket.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/net/tipc/socket.c b/net/tipc/socket.c
index 252a52ae0893261fc6f146ad81111c59f375fdce..6be21575503aa532014e7aa1415b2bf294757308 100644
--- a/net/tipc/socket.c
+++ b/net/tipc/socket.c
@@ -1516,10 +1516,10 @@ static void tipc_sk_set_orig_addr(struct msghdr *m, struct sk_buff *skb)
 
 	srcaddr->sock.family = AF_TIPC;
 	srcaddr->sock.addrtype = TIPC_ADDR_ID;
+	srcaddr->sock.scope = 0;
 	srcaddr->sock.addr.id.ref = msg_origport(hdr);
 	srcaddr->sock.addr.id.node = msg_orignode(hdr);
 	srcaddr->sock.addr.name.domain = 0;
-	srcaddr->sock.scope = 0;
 	m->msg_namelen = sizeof(struct sockaddr_tipc);
 
 	if (!msg_in_group(hdr))
@@ -1528,6 +1528,7 @@ static void tipc_sk_set_orig_addr(struct msghdr *m, struct sk_buff *skb)
 	/* Group message users may also want to know sending member's id */
 	srcaddr->member.family = AF_TIPC;
 	srcaddr->member.addrtype = TIPC_ADDR_NAME;
+	srcaddr->member.scope = 0;
 	srcaddr->member.addr.name.name.type = msg_nametype(hdr);
 	srcaddr->member.addr.name.name.instance = TIPC_SKB_CB(skb)->orig_member;
 	srcaddr->member.addr.name.domain = 0;
-- 
2.17.0.441.gb46fe60e1d-goog