From 95402143fe2f8b38280a727e8f0d5ec46813dedb Mon Sep 17 00:00:00 2001
From: homm <homm86@gmail.com>
Date: Mon, 20 Jun 2016 17:33:10 +0300
Subject: [PATCH] ignore large text blocks in PNG if LOAD_TRUNCATED_IMAGES is
 enabled

---
 PIL/PngImagePlugin.py  | 15 +++++++++++++++
 Tests/check_png_dos.py | 17 ++++++++++++++++-
 2 files changed, 31 insertions(+), 1 deletion(-)

diff --git a/PIL/PngImagePlugin.py b/PIL/PngImagePlugin.py
index 0e98dbf76..c6210c93a 100644
--- a/PIL/PngImagePlugin.py
+++ b/PIL/PngImagePlugin.py
@@ -311,6 +311,11 @@ class PngStream(ChunkStream):
                               comp_method)
         try:
             icc_profile = _safe_zlib_decompress(s[i+2:])
+        except ValueError:
+            if ImageFile.LOAD_TRUNCATED_IMAGES:
+                icc_profile = None
+            else:
+                raise
         except zlib.error:
             icc_profile = None  # FIXME
         self.im_info["icc_profile"] = icc_profile
@@ -430,6 +435,11 @@ class PngStream(ChunkStream):
                               comp_method)
         try:
             v = _safe_zlib_decompress(v[1:])
+        except ValueError:
+            if ImageFile.LOAD_TRUNCATED_IMAGES:
+                v = b""
+            else:
+                raise
         except zlib.error:
             v = b""
 
@@ -462,6 +472,11 @@ class PngStream(ChunkStream):
             if cm == 0:
                 try:
                     v = _safe_zlib_decompress(v)
+                except ValueError:
+                    if ImageFile.LOAD_TRUNCATED_IMAGES:
+                        return s
+                    else:
+                        raise
                 except zlib.error:
                     return s
             else:
diff --git a/Tests/check_png_dos.py b/Tests/check_png_dos.py
index c24eeb359..12c9955fb 100644
--- a/Tests/check_png_dos.py
+++ b/Tests/check_png_dos.py
@@ -1,5 +1,5 @@
 from helper import unittest, PillowTestCase
-from PIL import Image, PngImagePlugin
+from PIL import Image, PngImagePlugin, ImageFile
 from io import BytesIO
 import zlib
 
@@ -7,6 +7,21 @@ TEST_FILE = "Tests/images/png_decompression_dos.png"
 
 
 class TestPngDos(PillowTestCase):
+    def test_ignore_dos_text(self):
+        ImageFile.LOAD_TRUNCATED_IMAGES = True
+
+        try:
+            im = Image.open(TEST_FILE)
+            im.load()
+        finally:
+            ImageFile.LOAD_TRUNCATED_IMAGES = False
+
+        for s in im.text.values():
+            self.assertLess(len(s), 1024*1024, "Text chunk larger than 1M")
+
+        for s in im.info.values():
+            self.assertLess(len(s), 1024*1024, "Text chunk larger than 1M")
+
     def test_dos_text(self):
 
         try: