diff -up openssl-1.0.2k/crypto/x509v3/v3_addr.c.overread openssl-1.0.2k/crypto/x509v3/v3_addr.c
--- openssl-1.0.2k/crypto/x509v3/v3_addr.c.overread	2017-01-26 14:22:04.000000000 +0100
+++ openssl-1.0.2k/crypto/x509v3/v3_addr.c	2018-06-18 13:49:30.001625137 +0200
@@ -130,10 +130,12 @@ static int length_from_afi(const unsigne
  */
 unsigned int v3_addr_get_afi(const IPAddressFamily *f)
 {
-    return ((f != NULL &&
-             f->addressFamily != NULL && f->addressFamily->data != NULL)
-            ? ((f->addressFamily->data[0] << 8) | (f->addressFamily->data[1]))
-            : 0);
+    if (f == NULL
+            || f->addressFamily == NULL
+            || f->addressFamily->data == NULL
+            || f->addressFamily->length < 2)
+        return 0;
+    return (f->addressFamily->data[0] << 8) | f->addressFamily->data[1];
 }
 
 /*