Prevent overflow beyond the end of string in form_update_line()

Bug-Debian: https://github.com/tats/w3m/issues/78

1 files changed, 1 insertions, 1 deletions

diff --git a/form.c b/form.c
index 88b23b4..0dfbaa8 100644
--- a/form.c
+++ b/form.c
@@ -388,7 +388,7 @@ form_update_line(Line *line, char **str, int spos, int epos, int width,
 	prop[pos] = effect | PC_ASCII;
 	pos++;
     }
-    if (newline) {
+    if (p < q && newline) {
 	if (!FoldTextarea) {
 	    while (*p && *p != '\r' && *p != '\n')
 		p++;