tipc: fix nullptr crash during subscription cancel

[ Upstream commit 4de13d7ed6ffdcbb34317acaa9236f121176f5f8 ]

commit 4d5cfcba2f6e ('tipc: fix connection abort during subscription
cancel'), removes the check for a valid subscription before calling
tipc_nametbl_subscribe().

This will lead to a nullptr exception when we process a
subscription cancel request. For a cancel request, a null
subscription is passed to tipc_nametbl_subscribe() resulting
in exception.

In this commit, we call tipc_nametbl_subscribe() only for
a valid subscription.

Fixes: 4d5cfcba2f6e ('tipc: fix connection abort during subscription cancel')
Reported-by: Anders Widell <anders.widell@ericsson.com>
Signed-off-by: Parthasarathy Bhuvaragan <parthasarathy.bhuvaragan@ericsson.com>
Acked-by: Jon Maloy <jon.maloy@ericsson.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/net/tipc/subscr.c b/net/tipc/subscr.c
index 69ee2eeef968851192035cb166410f1f37e7722f..f9ff73a8d8154ff0a52f8c33a64077f5d8c57ae5 100644 (file)
--- a/net/tipc/subscr.c
+++ b/net/tipc/subscr.c
@@ -296,7 +296,8 @@ static void tipc_subscrb_rcv_cb(struct net *net, int conid,
        if (tipc_subscrp_create(net, (struct tipc_subscr *)buf, subscrb, &sub))
                return tipc_conn_terminate(tn->topsrv, subscrb->conid);
 
-       tipc_nametbl_subscribe(sub);
+       if (sub)
+               tipc_nametbl_subscribe(sub);
 }
 
 /* Handle one request to establish a new subscriber */