Memory error in Storage.c when accepting negative image size arguments

Author: wiredfool

Tests/images/negative_size.ppm

@@ -0,0 +1 @@
+P632 358888888632!

Tests/test_file_ppm.py

@@ -44,5 +44,17 @@ def test_truncated_file(self):
         self.assertRaises(ValueError, lambda: Image.open(path))
 
 
+    def test_neg_ppm(self):
+        """test_neg_ppm
+
+        Storage.c accepted negative values for xsize, ysize.
+        open_ppm is a core debugging item that doesn't check any parameters for
+        sanity. 
+        """
+        
+        with self.assertRaises(ValueError):
+            Image.core.open_ppm('Tests/images/negative_size.ppm')
+
+
 if __name__ == '__main__':
     unittest.main()

libImaging/Storage.c

@@ -406,6 +406,10 @@ ImagingNew(const char* mode, int xsize, int ysize)
     } else
         bytes = strlen(mode); /* close enough */
 
+    if (xsize < 0 || ysize < 0) {
+        return (Imaging) ImagingError_ValueError("bad image size");
+    }
+
     if ((int64_t) xsize * (int64_t) ysize <= THRESHOLD / bytes) {
         im = ImagingNewBlock(mode, xsize, ysize);
         if (im)