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>

1 files changed, 9 insertions, 3 deletions

diff --git a/net/sctp/proc.c b/net/sctp/proc.c
index 4e45ee3..0c83162 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();