Subject: Prevent deref null pointer in shiftAnchorPosition()
Author: Tatsuya Kinoshita <tats@debian.org>
Bug-Debian: https://github.com/tats/w3m/issues/40 [CVE-2016-9629]
Origin: https://anonscm.debian.org/cgit/collab-maint/w3m.git/commit/?id=a088e0263c48ba406a7ae0932a1ae64a25be7acd

diff --git a/anchor.c b/anchor.c
index e006aea..ecb211d 100644
--- a/anchor.c
+++ b/anchor.c
@@ -551,7 +551,7 @@ shiftAnchorPosition(AnchorList *al, HmarkerList *hl, int line, int pos,
 	    break;
 	if (a->start.pos > pos) {
 	    a->start.pos += shift;
-	    if (hl->marks[a->hseq].line == line)
+	    if (hl && hl->marks && hl->marks[a->hseq].line == line)
 		hl->marks[a->hseq].pos = a->start.pos;
 	}
 	if (a->end.pos >= pos)