Throw an exception when an opened image is larger than an arbitrary limit

PIL/Image.py

@@ -35,6 +35,12 @@ class _imaging_not_installed:
     def __getattr__(self, id):
         raise ImportError("The _imaging C module is not installed")
 
+
+class ImageIsTooBigError(Exception):
+    pass
+
+ARBITARY_LARGE_LIMIT = 6000 * 6000 - 1  # FIXME: Pick sensible limit
+
 try:
     # give Tk a chance to set up the environment, in case we're
     # using an _imaging module linked against libtcl/libtk (use
@@ -2100,7 +2106,18 @@ _fromarray_typemap[((1, 1), _ENDIAN + "i4")] = ("I", "I")
 _fromarray_typemap[((1, 1), _ENDIAN + "f4")] = ("F", "F")
 
 
-def open(fp, mode="r"):
+def _compression_bomb_check(im, maximum_pixels):
+    if maximum_pixels is None:
+        return
+
+    pixels = im.size[0] * im.size[1]
+    print("Pixels:", pixels)  # FIXME: temporary
+
+    if im.size[0] * im.size[1] > maximum_pixels:
+        raise ImageIsTooBigError("Image size exceeds limit")
+
+
+def open(fp, mode="r", maximum_pixels=ARBITARY_LARGE_LIMIT):
     """
     Opens and identifies the given image file.
 
@@ -2114,6 +2131,7 @@ def open(fp, mode="r"):
        must implement :py:meth:`~file.read`, :py:meth:`~file.seek`, and
        :py:meth:`~file.tell` methods, and be opened in binary mode.
     :param mode: The mode.  If given, this argument must be "r".
+    :param maximum_pixels: TODO.
     :returns: An :py:class:`~PIL.Image.Image` object.
     :exception IOError: If the file cannot be found, or the image cannot be
        opened and identified.
@@ -2137,7 +2155,10 @@ def open(fp, mode="r"):
             factory, accept = OPEN[i]
             if not accept or accept(prefix):
                 fp.seek(0)
-                return factory(fp, filename)
+                # return factory(fp, filename)
+                im = factory(fp, filename)
+                _compression_bomb_check(im, maximum_pixels)
+                return im
         except (SyntaxError, IndexError, TypeError):
             #import traceback
             #traceback.print_exc()
@@ -2150,7 +2171,10 @@ def open(fp, mode="r"):
                 factory, accept = OPEN[i]
                 if not accept or accept(prefix):
                     fp.seek(0)
-                    return factory(fp, filename)
+                    # return factory(fp, filename)
+                    im = factory(fp, filename)
+                    _compression_bomb_check(im, maximum_pixels)
+                    return im
             except (SyntaxError, IndexError, TypeError):
                 #import traceback
                 #traceback.print_exc()