Author: Tatsuya Kinoshita <tats@debian.org>
Subject: Prevent segfault with malformed input_alt
Bug-Debian: https://github.com/tats/w3m/issues/18 [CVE-2016-9438]
Origin: https://anonscm.debian.org/cgit/collab-maint/w3m.git/commit/?id=010b68580dc50ce183df11cc79721936ab5c4f25

diff --git a/file.c b/file.c
index 3b7befe..68d625c 100644
--- a/file.c
+++ b/file.c
@@ -3021,9 +3021,9 @@ flushline(struct html_feed_environ *h_env, struct readbuffer *obuf, int indent,
 	tmp = Sprintf("<INPUT_ALT hseq=\"%d\" fid=\"%d\" name=\"%s\" type=\"%s\" value=\"%s\">",
 		     obuf->input_alt.hseq,
 		     obuf->input_alt.fid,
-		     obuf->input_alt.name->ptr,
-		     obuf->input_alt.type->ptr,
-		     obuf->input_alt.value->ptr);
+		     obuf->input_alt.name ? obuf->input_alt.name->ptr : "",
+		     obuf->input_alt.type ? obuf->input_alt.type->ptr : "",
+		     obuf->input_alt.value ? obuf->input_alt.value->ptr : "");
 	push_tag(obuf, tmp->ptr, HTML_INPUT_ALT);
     }
     if (!hidden_bold && obuf->in_bold)