[net 1/1] tipc: fix missing initializer in tipc_sendmsg()

[Jon Maloy]

The stack variable 'dnode' in __tipc_sendmsg() may theoretically
end up tipc_node_get_mtu() as an unitilalized variable.

We fix this by intializing the variable at declaration. We also add
a default else clause to the two conditional ones already there, so
that we never end up in the named function if the given address
type is illegal.

Reported-by: syzbot+b0975ce9355b347c1...@syzkaller.appspotmail.com
Signed-off-by: Jon Maloy <jon.ma...@ericsson.com>
---
 net/tipc/socket.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/net/tipc/socket.c b/net/tipc/socket.c
index 1fd1c8b..252a52ae 100644
--- a/net/tipc/socket.c
+++ b/net/tipc/socket.c
@@ -1278,7 +1278,7 @@ static int __tipc_sendmsg(struct socket *sock, struct 
msghdr *m, size_t dlen)
        struct tipc_msg *hdr = &tsk->phdr;
        struct tipc_name_seq *seq;
        struct sk_buff_head pkts;
-       u32 dnode, dport;
+       u32 dport, dnode = 0;
        u32 type, inst;
        int mtu, rc;
 
@@ -1348,6 +1348,8 @@ static int __tipc_sendmsg(struct socket *sock, struct 
msghdr *m, size_t dlen)
                msg_set_destnode(hdr, dnode);
                msg_set_destport(hdr, dest->addr.id.ref);
                msg_set_hdr_sz(hdr, BASIC_H_SIZE);
+       } else {
+               return -EINVAL;
        }
 
        /* Block or return if destination link is congested */
-- 
2.1.4