--- camlimages-3.0.1/src/pngread.c	2007-01-18 10:29:57.000000000 +0000
+++ camlimages-3.0.1-oversized-png-checks/src/pngread.c	2009-07-03 14:19:42.000000000 +0100
@@ -26,6 +26,12 @@
 #define PNG_TAG_INDEX16 2
 #define PNG_TAG_INDEX4 3
 
+/* Test if x or y are negative, or if multiplying x * y would cause an
+ * arithmetic overflow.
+ */
+#define oversized(x, y)						\
+  ((x) < 0 || (y) < 0 || (x) * (y) < (x) || (x) * (y) < (y))
+
 value read_png_file_as_rgb24( name )
      value name;
 {
@@ -81,6 +87,9 @@
   png_get_IHDR(png_ptr, info_ptr, &width, &height, &bit_depth, &color_type,
 	       &interlace_type, NULL, NULL);
 
+  if (oversized (width, height))
+    failwith ("png error: image contains oversized or bogus width and height");
+
   if ( color_type == PNG_COLOR_TYPE_GRAY ||
        color_type == PNG_COLOR_TYPE_GRAY_ALPHA ) { 
     png_set_gray_to_rgb(png_ptr); 
@@ -102,6 +111,9 @@
 
   rowbytes = png_get_rowbytes(png_ptr, info_ptr);
 
+  if (oversized (rowbytes, height))
+    failwith ("png error: image contains oversized or bogus rowbytes and height");
+
   {
     int i;
     png_bytep *row_pointers;
@@ -235,6 +247,9 @@
   png_get_IHDR(png_ptr, info_ptr, &width, &height, &bit_depth, &color_type,
 	       &interlace_type, NULL, NULL);
 
+  if (oversized (width, height))
+    failwith ("png error: image contains oversized or bogus width and height");
+
   if ( color_type == PNG_COLOR_TYPE_GRAY ||
        color_type == PNG_COLOR_TYPE_GRAY_ALPHA ) { 
     png_set_gray_to_rgb(png_ptr); 
@@ -251,6 +266,9 @@
 
   rowbytes = png_get_rowbytes(png_ptr, info_ptr);
 
+  if (oversized (rowbytes, height))
+    failwith ("png error: image contains oversized or bogus rowbytes and height");
+
 /*
 fprintf(stderr, "pngread.c: actual loading\n"); fflush(stderr);
 */