Handle unexpected ICO image sizes

Tests/test_file_ico.py

@@ -83,3 +83,10 @@ def test_only_save_relevant_sizes(self):
         self.assertEqual(
             im_saved.info['sizes'],
             {(16, 16), (24, 24), (32, 32), (48, 48)})
+
+    def test_unexpected_size(self):
+        # This image has been manually hexedited to state that it is 16x32
+        # while the image within is still 16x16
+        im = self.assert_warning(UserWarning,
+                                 Image.open, "Tests/images/hopper_unexpected.ico")
+        self.assertEqual(im.size, (16, 16))

src/PIL/IcoImagePlugin.py

@@ -23,6 +23,7 @@
 
 
 import struct
+import warnings
 from io import BytesIO
 
 from . import Image, ImageFile, BmpImagePlugin, PngImagePlugin
@@ -143,14 +144,17 @@ def sizes(self):
         """
         return {(h['width'], h['height']) for h in self.entry}
 
+    def getentryindex(self, size, bpp=False):
+        for (i, h) in enumerate(self.entry):
+            if size == h['dim'] and (bpp is False or bpp == h['color_depth']):
+                return i
+        return 0
+
     def getimage(self, size, bpp=False):
         """
         Get an image from the icon
         """
-        for (i, h) in enumerate(self.entry):
-            if size == h['dim'] and (bpp is False or bpp == h['color_depth']):
-                return self.frame(i)
-        return self.frame(0)
+        return self.frame(self.getentryindex(size, bpp))
 
     def frame(self, idx):
         """
@@ -282,6 +286,13 @@ def load(self):
         im.load()
         self.im = im.im
         self.mode = im.mode
+        if im.size != self.size:
+            warnings.warn("Image was not the expected size")
+
+            index = self.ico.getentryindex(self.size)
+            sizes = list(self.info['sizes'])
+            sizes[index] = im.size
+            self.info['sizes'] = set(sizes)
         self.size = im.size
 
     def load_seek(self):