From 4e7c55aabfd567e60542f7a2d09419226653ff72 Mon Sep 17 00:00:00 2001 From: Tuong Lien Date: Tue, 10 Dec 2019 15:21:04 +0700 Subject: [PATCH] tipc: fix retrans failure due to wrong destination commit abc9b4e0549b93fdaff56e9532bc49a2d7b04955 upstream. When a user message is sent, TIPC will check if the socket has faced a congestion at link layer. If that happens, it will make a sleep to wait for the congestion to disappear. This leaves a gap for other users to take over the socket (e.g. multi threads) since the socket is released as well. Also, in case of connectionless (e.g. SOCK_RDM), user is free to send messages to various destinations (e.g. via 'sendto()'), then the socket's preformatted header has to be updated correspondingly prior to the actual payload message building. Unfortunately, the latter action is done before the first action which causes a condition issue that the destination of a certain message can be modified incorrectly in the middle, leading to wrong destination when that message is built. Consequently, when the message is sent to the link layer, it gets stuck there forever because the peer node will simply reject it. After a number of retransmission attempts, the link is eventually taken down and the retransmission failure is reported. This commit fixes the problem by rearranging the order of actions to prevent the race condition from occurring, so the message building is 'atomic' and its header will not be modified by anyone. Fixes: 365ad353c256 ("tipc: reduce risk of user starvation during link congestion") Acked-by: Jon Maloy Signed-off-by: Tuong Lien Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- net/tipc/socket.c | 32 ++++++++++++++++++-------------- 1 file changed, 18 insertions(+), 14 deletions(-) diff --git a/net/tipc/socket.c b/net/tipc/socket.c index 4b92b19..79d06c2 100644 --- a/net/tipc/socket.c +++ b/net/tipc/socket.c @@ -1306,8 +1306,8 @@ 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 dport, dnode = 0; - u32 type, inst; + u32 dport = 0, dnode = 0; + u32 type = 0, inst = 0; int mtu, rc; if (unlikely(dlen > TIPC_MAX_USER_MSG_SIZE)) @@ -1360,23 +1360,11 @@ static int __tipc_sendmsg(struct socket *sock, struct msghdr *m, size_t dlen) type = dest->addr.name.name.type; inst = dest->addr.name.name.instance; dnode = dest->addr.name.domain; - msg_set_type(hdr, TIPC_NAMED_MSG); - msg_set_hdr_sz(hdr, NAMED_H_SIZE); - msg_set_nametype(hdr, type); - msg_set_nameinst(hdr, inst); - msg_set_lookup_scope(hdr, tipc_node2scope(dnode)); dport = tipc_nametbl_translate(net, type, inst, &dnode); - msg_set_destnode(hdr, dnode); - msg_set_destport(hdr, dport); if (unlikely(!dport && !dnode)) return -EHOSTUNREACH; } else if (dest->addrtype == TIPC_ADDR_ID) { dnode = dest->addr.id.node; - msg_set_type(hdr, TIPC_DIRECT_MSG); - msg_set_lookup_scope(hdr, 0); - msg_set_destnode(hdr, dnode); - msg_set_destport(hdr, dest->addr.id.ref); - msg_set_hdr_sz(hdr, BASIC_H_SIZE); } else { return -EINVAL; } @@ -1387,6 +1375,22 @@ static int __tipc_sendmsg(struct socket *sock, struct msghdr *m, size_t dlen) if (unlikely(rc)) return rc; + if (dest->addrtype == TIPC_ADDR_NAME) { + msg_set_type(hdr, TIPC_NAMED_MSG); + msg_set_hdr_sz(hdr, NAMED_H_SIZE); + msg_set_nametype(hdr, type); + msg_set_nameinst(hdr, inst); + msg_set_lookup_scope(hdr, tipc_node2scope(dnode)); + msg_set_destnode(hdr, dnode); + msg_set_destport(hdr, dport); + } else { /* TIPC_ADDR_ID */ + msg_set_type(hdr, TIPC_DIRECT_MSG); + msg_set_lookup_scope(hdr, 0); + msg_set_destnode(hdr, dnode); + msg_set_destport(hdr, dest->addr.id.ref); + msg_set_hdr_sz(hdr, BASIC_H_SIZE); + } + __skb_queue_head_init(&pkts); mtu = tipc_node_get_mtu(net, dnode, tsk->portid); rc = tipc_msg_build(hdr, m, 0, dlen, mtu, &pkts); -- 2.7.4