Fix seg fault in json parser

Author: mikkelfj

CHANGELOG.md

@@ -16,7 +16,8 @@
   Windows build is included it only covers recent 64-bit Windows. More
   work is need for older Windows variants. (#250).
 - Increase maximum allowed schema file size from 64 KiB to 1 MB (#256).
-
+- Fix seg fault in json parser while adding null characters to a too
+  short input string for a fixed length char array struct field (#257).
 
 ## [0.6.1]
 

src/runtime/json_parser.c

@@ -879,7 +879,7 @@ const char *flatcc_json_parser_char_array(flatcc_json_parser_t *ctx,
         if (ctx->flags & flatcc_json_parser_f_reject_array_underflow) {
             return flatcc_json_parser_set_error(ctx, buf, end, flatcc_json_parser_error_array_underflow);
         }
-        memset(s, 0, n - k);
+        memset(s, 0, n);
     }
     return flatcc_json_parser_string_end(ctx, buf, end);
 }