Merge pull request #2583 from wiredfool/decompression_bomb_error

Decompression bomb error

PIL/Image.py

@@ -36,6 +36,8 @@ logger = logging.getLogger(__name__)
 class DecompressionBombWarning(RuntimeWarning):
     pass
 
+class DecompressionBombError(Exception):
+    pass
 
 class _imaging_not_installed(object):
     # module placeholder
@@ -2493,6 +2495,12 @@ def _decompression_bomb_check(size):
 
     pixels = size[0] * size[1]
 
+    if pixels > 2 * MAX_IMAGE_PIXELS:
+        raise DecompressionBombError(
+            "Image size (%d pixels) exceeds limit of %d pixels, "
+            "could be decompression bomb DOS attack." %
+            (pixels, 2* MAX_IMAGE_PIXELS))
+
     if pixels > MAX_IMAGE_PIXELS:
         warnings.warn(
             "Image size (%d pixels) exceeds limit of %d pixels, "

Tests/test_decompression_bomb.py

@@ -29,20 +29,26 @@ class TestDecompressionBomb(PillowTestCase):
         Image.open(TEST_FILE)
 
     def test_warning(self):
-        # Arrange
-        # Set limit to a low, easily testable value
-        Image.MAX_IMAGE_PIXELS = 10
-        self.assertEqual(Image.MAX_IMAGE_PIXELS, 10)
+        # Set limit to trigger warning on the test file
+        Image.MAX_IMAGE_PIXELS = 128 * 128 -1
+        self.assertEqual(Image.MAX_IMAGE_PIXELS, 128 * 128 - 1)
 
-        # Act / Assert
         self.assert_warning(Image.DecompressionBombWarning,
                             Image.open, TEST_FILE)
 
+    def test_exception(self):
+        # Set limit to trigger exception on the test file
+        Image.MAX_IMAGE_PIXELS = 64 * 128 -1
+        self.assertEqual(Image.MAX_IMAGE_PIXELS, 64 * 128 - 1)
+
+        self.assertRaises(Image.DecompressionBombError,
+                          lambda: Image.open(TEST_FILE))
+
 class TestDecompressionCrop(PillowTestCase):
 
     def setUp(self):
         self.src = hopper()
-        Image.MAX_IMAGE_PIXELS = self.src.height * self.src.width
+        Image.MAX_IMAGE_PIXELS = self.src.height * self.src.width * 4 - 1
 
     def tearDown(self):
         Image.MAX_IMAGE_PIXELS = ORIGINAL_LIMIT
@@ -54,5 +60,6 @@ class TestDecompressionCrop(PillowTestCase):
         self.assert_warning(Image.DecompressionBombWarning,
                             self.src.crop, box)
 
+
 if __name__ == '__main__':
     unittest.main()