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Merge pull request #1805 from wiredfool/verify-struct-error

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Catch struct.errors when verifying png files
This commit is contained in:
Hugo 2016-04-04 16:38:29 +03:00
commit cee9a1da15
2 changed files with 33 additions and 7 deletions
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24
PIL/PngImagePlugin.py
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@ -36,6 +36,7 @@ from __future__ import print_function
import logging
import re
import zlib
import struct
from PIL import Image, ImageFile, ImagePalette, _binary
@ -106,6 +107,7 @@ class ChunkStream(object):
def read(self):
"Fetch a new chunk. Returns header information."
cid = None
if self.queue:
cid, pos, length = self.queue[-1]
@ -116,7 +118,7 @@ class ChunkStream(object):
cid = s[4:]
pos = self.fp.tell()
length = i32(s)
if not is_cid(cid):
raise SyntaxError("broken PNG file (chunk %s)" % repr(cid))
@ -138,11 +140,15 @@ class ChunkStream(object):
def crc(self, cid, data):
"Read and verify checksum"
crc1 = Image.core.crc32(data, Image.core.crc32(cid))
crc2 = i16(self.fp.read(2)), i16(self.fp.read(2))
if crc1 != crc2:
raise SyntaxError("broken PNG file"
"(bad header checksum in %s)" % cid)
try:
crc1 = Image.core.crc32(data, Image.core.crc32(cid))
crc2 = i16(self.fp.read(2)), i16(self.fp.read(2))
if crc1 != crc2:
raise SyntaxError("broken PNG file (bad header checksum in %s)"
% cid)
except struct.error:
raise SyntaxError("broken PNG file (incomplete checksum in %s)"
% cid)
def crc_skip(self, cid, data):
"Read checksum. Used if the C module is not present"
@ -157,7 +163,11 @@ class ChunkStream(object):
cids = []
while True:
cid, pos, length = self.read()
try:
cid, pos, length = self.read()
except struct.error:
raise IOError("truncated PNG file")
if cid == endchunk:
break
self.crc(cid, ImageFile._safe_read(self.fp, length))

16
Tests/test_file_png.py
View File

@ -253,6 +253,22 @@ class TestFilePng(PillowTestCase):
im.load()
self.assertRaises(RuntimeError, im.verify)
def test_verify_struct_error(self):
# Check open/load/verify exception (#1755)
# offsets to test, -10: breaks in i32() in read. (IOError)
# -13: breaks in crc, txt chunk.
# -14: malformed chunk
for offset in (-10, -13, -14):
with open(TEST_PNG_FILE,'rb') as f:
test_file = f.read()[:offset]
im = Image.open(BytesIO(test_file))
self.assertTrue(im.fp is not None)
self.assertRaises((IOError, SyntaxError), im.verify)
def test_roundtrip_dpi(self):
# Check dpi roundtripping