[PATCH AUTOSEL for 4.15 007/189] tipc: fix a potental access after delete in tipc_sk_join()

[Sasha Levin]

From: Jon Maloy <jon.maloy@xxxxxxxxxxxx>

[ Upstream commit febafc8455fdbb0ba53d596075068a683b75f355 ]

In commit d12d2e12cec2 "tipc: send out join messages as soon as new
member is discovered") we added a call to the function tipc_group_join()
without considering the case that the preceding tipc_sk_publish() might
have failed, and the group item already deleted.

We fix this by returning from tipc_sk_join() directly after the
failed tipc_sk_publish.

Reported-by: syzbot+e3eeae78ea88b8d6d858@xxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Jon Maloy <jon.maloy@xxxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxxxx>
---
 net/tipc/socket.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/net/tipc/socket.c b/net/tipc/socket.c
index 3b4084480377..8efd2e42de30 100644
--- a/net/tipc/socket.c
+++ b/net/tipc/socket.c
@@ -2759,6 +2759,7 @@ static int tipc_sk_join(struct tipc_sock *tsk, struct tipc_group_req *mreq)
 	if (rc) {
 		tipc_group_delete(net, grp);
 		tsk->group = NULL;
+		return rc;
 	}
 
 	/* Eliminate any risk that a broadcast overtakes the sent JOIN */
-- 
2.15.1