Merge branch '26-potential-integer-overflow-vulnerability' into 'master'

Resolve "Potential Integer Overflow vulnerability"

Closes #26

See merge request sane-project/frontends!28

src/preview.c

@@ -1159,11 +1159,28 @@ restore_preview_image (Preview * p)
   p->image_height = height;
   if ((width == 0) || (height == 0))
     return;
-  p->image_data = malloc (3 * width * height);
+
-  p->preview_data = malloc (3 * width * height);
+  int data_size = 3 * width * height;
+
+  // Overflow check.
+  if ((data_size / width) / height != 3)
+    {
+      // overflow occurred. Ignore the image. The dimensions are probably corrupted.
+      return;
+    }
+
+  p->image_data = malloc (data_size);
   if (!p->image_data)
     return;
 
+  p->preview_data = malloc (data_size);
+  if (!p->preview_data)
+    {
+      free(p->image_data);
+      p->image_data = NULL;
+      return;
+    }
+
   nread = fread (p->image_data, 3, width * height, in);
 
   p->image_y = nread / width;