diff --git a/CHANGES.rst b/CHANGES.rst index fec47bf5b..e1abb0d7d 100644 --- a/CHANGES.rst +++ b/CHANGES.rst @@ -1,6 +1,12 @@ Changelog (Pillow) ================== +2.6.2 (2015-01-01) +------------------ + +- Fix potential PNG decompression DOS #1060 + [wiredfool] + 2.6.1 (2014-10-13) ------------------ diff --git a/PIL/PngImagePlugin.py b/PIL/PngImagePlugin.py index 2110aa637..598395c0a 100644 --- a/PIL/PngImagePlugin.py +++ b/PIL/PngImagePlugin.py @@ -72,6 +72,19 @@ _MODES = { _simple_palette = re.compile(b'^\xff+\x00\xff*$') +# Maximum decompressed size for a iTXt or zTXt chunk. +# Eliminates decompression bombs where compressed chunks can expand 1000x +MAX_TEXT_CHUNK = ImageFile.SAFEBLOCK +# Set the maximum total text chunk size. +MAX_TEXT_MEMORY = 64 * MAX_TEXT_CHUNK + +def _safe_zlib_decompress(s): + dobj = zlib.decompressobj() + plaintext = dobj.decompress(s, MAX_TEXT_CHUNK) + if dobj.unconsumed_tail: + raise ValueError("Decompressed Data Too Large") + return plaintext + # -------------------------------------------------------------------- # Support classes. Suitable for PNG and related formats like MNG etc. @@ -184,7 +197,6 @@ class PngInfo: tkey = tkey.encode("utf-8", "strict") if zip: - import zlib self.add(b"iTXt", key + b"\0\x01\0" + lang + b"\0" + tkey + b"\0" + zlib.compress(value)) else: @@ -206,7 +218,6 @@ class PngInfo: key = key.encode('latin-1', 'strict') if zip: - import zlib self.add(b"zTXt", key + b"\0\0" + zlib.compress(value)) else: self.add(b"tEXt", key + b"\0" + value) @@ -229,6 +240,14 @@ class PngStream(ChunkStream): self.im_tile = None self.im_palette = None + self.text_memory = 0 + + def check_text_memory(self, chunklen): + self.text_memory += chunklen + if self.text_memory > MAX_TEXT_MEMORY: + raise ValueError("Too much memory used in text chunks: %s>MAX_TEXT_MEMORY" % + self.text_memory) + def chunk_iCCP(self, pos, length): # ICC profile @@ -247,7 +266,7 @@ class PngStream(ChunkStream): raise SyntaxError("Unknown compression method %s in iCCP chunk" % comp_method) try: - icc_profile = zlib.decompress(s[i+2:]) + icc_profile = _safe_zlib_decompress(s[i+2:]) except zlib.error: icc_profile = None # FIXME self.im_info["icc_profile"] = icc_profile @@ -341,6 +360,8 @@ class PngStream(ChunkStream): v = v.decode('latin-1', 'replace') self.im_info[k] = self.im_text[k] = v + self.check_text_memory(len(v)) + return s def chunk_zTXt(self, pos, length): @@ -359,9 +380,8 @@ class PngStream(ChunkStream): if comp_method != 0: raise SyntaxError("Unknown compression method %s in zTXt chunk" % comp_method) - import zlib try: - v = zlib.decompress(v[1:]) + v = _safe_zlib_decompress(v[1:]) except zlib.error: v = b"" @@ -371,6 +391,8 @@ class PngStream(ChunkStream): v = v.decode('latin-1', 'replace') self.im_info[k] = self.im_text[k] = v + self.check_text_memory(len(v)) + return s def chunk_iTXt(self, pos, length): @@ -390,9 +412,8 @@ class PngStream(ChunkStream): return s if cf != 0: if cm == 0: - import zlib try: - v = zlib.decompress(v) + v = _safe_zlib_decompress(v) except zlib.error: return s else: @@ -407,7 +428,8 @@ class PngStream(ChunkStream): return s self.im_info[k] = self.im_text[k] = iTXt(v, lang, tk) - + self.check_text_memory(len(v)) + return s diff --git a/PIL/__init__.py b/PIL/__init__.py index c7a102d08..6de3caef0 100644 --- a/PIL/__init__.py +++ b/PIL/__init__.py @@ -12,7 +12,7 @@ # ;-) VERSION = '1.1.7' # PIL version -PILLOW_VERSION = '2.6.1' # Pillow +PILLOW_VERSION = '2.6.2' # Pillow _plugins = ['BmpImagePlugin', 'BufrStubImagePlugin', diff --git a/Tests/check_png_dos.py b/Tests/check_png_dos.py new file mode 100644 index 000000000..c74990a8c --- /dev/null +++ b/Tests/check_png_dos.py @@ -0,0 +1,47 @@ +from helper import unittest, PillowTestCase +from PIL import Image, PngImagePlugin +from io import BytesIO +import zlib + +TEST_FILE = "Tests/images/png_decompression_dos.png" + +class TestPngDos(PillowTestCase): + def test_dos_text(self): + + try: + im = Image.open(TEST_FILE) + im.load() + except ValueError as msg: + self.assertTrue(msg, "Decompressed Data Too Large") + return + + for s in im.text.values(): + self.assertLess(len(s), 1024*1024, "Text chunk larger than 1M") + + def test_dos_total_memory(self): + im = Image.new('L',(1,1)) + compressed_data = zlib.compress('a'*1024*1023) + + info = PngImagePlugin.PngInfo() + + for x in range(64): + info.add_text('t%s'%x, compressed_data, 1) + info.add_itxt('i%s'%x, compressed_data, zip=True) + + b = BytesIO() + im.save(b, 'PNG', pnginfo=info) + b.seek(0) + + try: + im2 = Image.open(b) + except ValueError as msg: + self.assertIn("Too much memory", msg) + return + + total_len = 0 + for txt in im2.text.values(): + total_len += len(txt) + self.assertLess(total_len, 64*1024*1024, "Total text chunks greater than 64M") + +if __name__ == '__main__': + unittest.main() diff --git a/Tests/images/png_decompression_dos.png b/Tests/images/png_decompression_dos.png new file mode 100644 index 000000000..986561b2e Binary files /dev/null and b/Tests/images/png_decompression_dos.png differ diff --git a/Tests/test_file_png.py b/Tests/test_file_png.py index 7a43414eb..b556199f5 100644 --- a/Tests/test_file_png.py +++ b/Tests/test_file_png.py @@ -153,7 +153,7 @@ class TestFilePng(PillowTestCase): im = load(HEAD + chunk(b'iTXt', b'spam\0\1\0en\0Spam\0' + zlib.compress(b"egg")[:1]) + TAIL) - self.assertEqual(im.info, {}) + self.assertEqual(im.info, {'spam':''}) im = load(HEAD + chunk(b'iTXt', b'spam\0\1\1en\0Spam\0' + zlib.compress(b"egg")) + TAIL) diff --git a/_imaging.c b/_imaging.c index a7605b1ee..e963e8c2f 100644 --- a/_imaging.c +++ b/_imaging.c @@ -71,7 +71,7 @@ * See the README file for information on usage and redistribution. */ -#define PILLOW_VERSION "2.6.1" +#define PILLOW_VERSION "2.6.2" #include "Python.h" diff --git a/docs/handbook/image-file-formats.rst b/docs/handbook/image-file-formats.rst index 31adcb142..34839caaa 100644 --- a/docs/handbook/image-file-formats.rst +++ b/docs/handbook/image-file-formats.rst @@ -332,6 +332,14 @@ The :py:meth:`~PIL.Image.Image.open` method sets the following Transparency color index. This key is omitted if the image is not a transparent palette image. +``Open`` also sets ``Image.text`` to a list of the values of the +``tEXt``, ``zTXt``, and ``iTXt`` chunks of the PNG image. Individual +compressed chunks are limited to a decompressed size of +``PngImagePlugin.MAX_TEXT_CHUNK``, by default 1MB, to prevent +decompression bombs. Additionally, the total size of all of the text +chunks is limited to ``PngImagePlugin.MAX_TEXT_MEMORY``, defaulting to +64MB. + The :py:meth:`~PIL.Image.Image.save` method supports the following options: **optimize** diff --git a/setup.py b/setup.py index 3b282f1c0..ac41c51ab 100644 --- a/setup.py +++ b/setup.py @@ -90,7 +90,7 @@ except (ImportError, OSError): NAME = 'Pillow' -PILLOW_VERSION = '2.6.1' +PILLOW_VERSION = '2.6.2' TCL_ROOT = None JPEG_ROOT = None JPEG2K_ROOT = None