Subject: Prevent segfault with incorrect button type
Author: Tatsuya Kinoshita <tats@debian.org>
Bug-Debian: https://github.com/tats/w3m/issues/17 [CVE-2016-9437]
Origin: https://anonscm.debian.org/cgit/collab-maint/w3m.git/commit/?id=67be73b03a5ad581e331ec97cb275cd8a52719ed

diff --git a/file.c b/file.c
index b30aa6b..3b7befe 100644
--- a/file.c
+++ b/file.c
@@ -3756,6 +3756,17 @@ process_button(struct parsed_tag *tag)
     if (v == FORM_UNKNOWN)
        return NULL;
 
+    switch (v) {
+    case FORM_INPUT_SUBMIT:
+    case FORM_INPUT_BUTTON:
+    case FORM_INPUT_RESET:
+	break;
+    default:
+	p = "submit";
+	v = FORM_INPUT_SUBMIT;
+	break;
+    }
+
     if (!q) {
        switch (v) {
        case FORM_INPUT_SUBMIT: