add limitation to width and height

Author: knok

include/sixel.h.in

@@ -366,6 +366,9 @@ typedef int SIXELSTATUS;
 #define SIXEL_OPTFLAG_VERSION           ('V')  /* -V, --version: show version and license info */
 #define SIXEL_OPTFLAG_HELP              ('H')  /* -H, --help: show this help */
 
+#define SIXEL_WIDTH_LIMIT               1000000
+#define SIXEL_HEIGHT_LIMIT              1000000
+
 #if SIXEL_USE_DEPRECATED_SYMBOLS
 /* output character size */
 enum characterSize {

src/decoder.c

@@ -315,6 +315,11 @@ sixel_decoder_decode(
         goto end;
     }
 
+    if (sx > SIXEL_WIDTH_LIMIT || sy > SIXEL_HEIGHT_LIMIT) {
+        status = SIXEL_BAD_INPUT;
+        goto end;
+    }
+
     status = sixel_helper_write_image_file(indexed_pixels, sx, sy, palette,
                                            SIXEL_PIXELFORMAT_PAL8,
                                            decoder->output,