From 1bfb0b5247f4fc8f6677639781ce468543490216 Mon Sep 17 00:00:00 2001
From: DRC <information@libjpeg-turbo.org>
Date: Tue, 2 Jun 2020 14:15:37 -0500
Subject: [PATCH] rdppm.c: Fix buf overrun caused by bad binary PPM

This extends the fix in 1e81b0c3ea26f4ea8f56de05367469333de64a9f to
include binary PPM files with maximum values < 255, thus preventing a
malformed binary PPM input file with those specifications from
triggering an overrun of the rescale array and potentially crashing
cjpeg, TJBench, or any program that uses the tjLoadImage() function.

Fixes #433
diff --git a/rdppm.c b/rdppm.c
index c0c096218..899436eec 100644
--- a/rdppm.c
+++ b/rdppm.c
@@ -5,7 +5,7 @@
  * Copyright (C) 1991-1997, Thomas G. Lane.
  * Modified 2009 by Bill Allombert, Guido Vollbeding.
  * libjpeg-turbo Modifications:
- * Copyright (C) 2015, 2016, D. R. Commander.
+ * Copyright (C) 2015, 2016, 2020, D. R. Commander.
  * For conditions of distribution and use, see the accompanying README.ijg
  * file.
  *
@@ -22,6 +22,7 @@
  * the file is indeed PPM format).
  */
 
+#define JPEG_INTERNALS
 #include "cdjpeg.h"             /* Common decls for cjpeg/djpeg applications */
 
 #ifdef PPM_SUPPORTED
@@ -425,7 +426,7 @@ start_input_ppm (j_compress_ptr cinfo, cjpeg_source_ptr sinfo)
     /* On 16-bit-int machines we have to be careful of maxval = 65535 */
     source->rescale = (JSAMPLE *)
       (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
-                                  (size_t) (((long) maxval + 1L) *
+                                  (size_t) (((long) MAX(maxval, 255) + 1L) *
                                             sizeof(JSAMPLE)));
     half_maxval = maxval / 2;
     for (val = 0; val <= (long) maxval; val++) {