From 67e8b08bbef5c005ebb92ee26887f1e7914bae10 Mon Sep 17 00:00:00 2001
From: Michael Tuexen <tuexen@FreeBSD.org>
Date: Sun, 6 May 2018 14:19:50 +0000
Subject: [PATCH] Ensure we are not dereferencing a NULL pointer.

This was found by Coverity scanning the usrsctp stack (CID 203808).

MFC after:	3 days
---
 sys/netinet/sctp_indata.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/sys/netinet/sctp_indata.c b/sys/netinet/sctp_indata.c
index cbd2cf6dbe7..b08c32f30a5 100644
--- a/sys/netinet/sctp_indata.c
+++ b/sys/netinet/sctp_indata.c
@@ -3621,7 +3621,9 @@ sctp_strike_gap_ack_chunks(struct sctp_tcb *stcb, struct sctp_association *asoc,
 						    SCTP_SO_NOT_LOCKED);
 					}
 					/* Make sure to flag we had a FR */
-					tp1->whoTo->net_ack++;
+					if (tp1->whoTo != NULL) {
+						tp1->whoTo->net_ack++;
+					}
 					continue;
 				}
 			}