From ab57858195cf7fa3bbc24a291d51b382ef18bfbf Mon Sep 17 00:00:00 2001
From: wolfbeast <mcwerewolf@gmail.com>
Date: Tue, 29 May 2018 13:11:09 +0200
Subject: Limit PNG image dimensions.

---
 image/decoders/nsPNGDecoder.cpp | 18 +++++++++++++++---
 1 file changed, 15 insertions(+), 3 deletions(-)

(limited to 'image')

diff --git a/image/decoders/nsPNGDecoder.cpp b/image/decoders/nsPNGDecoder.cpp
index 0f385b339..9596ae7d6 100644
--- a/image/decoders/nsPNGDecoder.cpp
+++ b/image/decoders/nsPNGDecoder.cpp
@@ -34,13 +34,18 @@ namespace image {
 static LazyLogModule sPNGLog("PNGDecoder");
 static LazyLogModule sPNGDecoderAccountingLog("PNGDecoderAccounting");
 
-// limit image dimensions (bug #251381, #591822, #967656, and #1283961)
+// Limit image dimensions.
 #ifndef MOZ_PNG_MAX_WIDTH
-#  define MOZ_PNG_MAX_WIDTH 0x7fffffff // Unlimited
+#  define MOZ_PNG_MAX_WIDTH 65535
 #endif
 #ifndef MOZ_PNG_MAX_HEIGHT
-#  define MOZ_PNG_MAX_HEIGHT 0x7fffffff // Unlimited
+#  define MOZ_PNG_MAX_HEIGHT 65535
 #endif
+// Maximum area supported in pixels (W*H)
+#ifndef MOZ_PNG_MAX_PIX
+#  define MOZ_PNG_MAX_PIX 268435456 // 256 Mpix = 16Ki x 16Ki
+#endif
+
 
 nsPNGDecoder::AnimFrameInfo::AnimFrameInfo()
  : mDispose(DisposalMethod::KEEP)
@@ -568,6 +573,13 @@ nsPNGDecoder::info_callback(png_structp png_ptr, png_infop info_ptr)
   png_get_IHDR(png_ptr, info_ptr, &width, &height, &bit_depth, &color_type,
                &interlace_type, &compression_type, &filter_type);
 
+  // Check sizes against cap limits and W*H
+  if ((width > MOZ_PNG_MAX_WIDTH) ||
+      (height > MOZ_PNG_MAX_HEIGHT) ||
+      (width * height > MOZ_PNG_MAX_PIX)) {
+    png_error(decoder->mPNG, "Image too large");
+  }  
+
   const IntRect frameRect(0, 0, width, height);
 
   // Post our size to the superclass
-- 
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