net: sctp: sideeffect: throw BUG if primary_path is NULL

This clearly states a BUG somewhere in the SCTP code as e.g. fixed once
in f28156335 ("sctp: Use correct sideffect command in duplicate cookie
handling"). If this ever happens, throw a trace in the sideeffect engine
where assocs clearly must have a primary_path assigned.

When in sctp_seq_dump_local_addrs() also throw a WARN and bail out since
we do not need to panic for printing this one asterisk. Also, it will
avoid the not so obvious case when primary != NULL test passes and at a
later point in time triggering a NULL ptr dereference caused by primary.
While at it, also fix up the white space.

Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Acked-by: Vlad Yasevich <vyasevich@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 13 insertions, 4 deletions

diff --git a/net/sctp/proc.c b/net/sctp/proc.c
index 4e45ee35d0db..0c83162a6bf8 100644
--- a/net/sctp/proc.c
+++ b/net/sctp/proc.c
@@ -134,9 +134,15 @@ static void sctp_seq_dump_local_addrs(struct seq_file *seq, struct sctp_ep_commo
         struct sctp_af *af;
 
         if (epb->type == SCTP_EP_TYPE_ASSOCIATION) {
-            asoc = sctp_assoc(epb);
-            peer = asoc->peer.primary_path;
-            primary = &peer->saddr;
+                asoc = sctp_assoc(epb);
+
+                peer = asoc->peer.primary_path;
+                if (unlikely(peer == NULL)) {
+                        WARN(1, "Association %p with NULL primary path!", asoc);
+                        return;
+                }
+
+                primary = &peer->saddr;
         }
 
         rcu_read_lock();
diff --git a/net/sctp/sm_sideeffect.c b/net/sctp/sm_sideeffect.c
index 8aab894aeabe..ff91f47b0239 100644
--- a/net/sctp/sm_sideeffect.c
+++ b/net/sctp/sm_sideeffect.c
@@ -864,6 +864,7 @@ static void sctp_cmd_delete_tcb(sctp_cmd_seq_t *cmds,
             (!asoc->temp) && (sk->sk_shutdown != SHUTDOWN_MASK))
                 return;
 
+        BUG_ON(asoc->peer.primary_path == NULL);
         sctp_unhash_established(asoc);
         sctp_association_free(asoc);
 }
@@ -1274,8 +1275,10 @@ static int sctp_cmd_interpreter(sctp_event_t event_type,
                                 sctp_outq_uncork(&asoc->outqueue);
                                 local_cork = 0;
                         }
-                        asoc = cmd->obj.asoc;
+
                         /* Register with the endpoint.  */
+                        asoc = cmd->obj.asoc;
+                        BUG_ON(asoc->peer.primary_path == NULL);
                         sctp_endpoint_add_asoc(ep, asoc);
                         sctp_hash_established(asoc);
                         break;