tipc: fix a dangling pointer

tsk->group is set to grp earlier, but we forget to unset it
after grp is freed.

Fixes: 75da2163dbb6 ("tipc: introduce communication groups")
Reported-by: syzkaller bot
Cc: Jon Maloy <jon.maloy@ericsson.com>
Cc: Ying Xue <ying.xue@windriver.com>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/tipc/socket.c b/net/tipc/socket.c
index b3b72d8e95438336c6e90bd4d58b9bdca33cd2ca..ea61c32f6b807a63a274710848fab3e4ceb9f152 100644 (file)
--- a/net/tipc/socket.c
+++ b/net/tipc/socket.c
@@ -2756,8 +2756,10 @@ static int tipc_sk_join(struct tipc_sock *tsk, struct tipc_group_req *mreq)
        seq.upper = seq.lower;
        tipc_nametbl_build_group(net, grp, mreq->type, domain);
        rc = tipc_sk_publish(tsk, mreq->scope, &seq);
-       if (rc)
+       if (rc) {
                tipc_group_delete(net, grp);
+               tsk->group = NULL;
+       }
 
        /* Eliminate any risk that a broadcast overtakes the sent JOIN */
        tsk->mc_method.rcast = true;