gdi32: Check header pointer in CreateDIBitmap.
diff --git a/dlls/gdi32/dib.c b/dlls/gdi32/dib.c
index 0dceaa8..086eaae 100644
--- a/dlls/gdi32/dib.c
+++ b/dlls/gdi32/dib.c
@@ -1097,6 +1097,8 @@
     DWORD compr, size;
     DC *dc;
 
+    if (!header) return 0;
+
     if (DIB_GetBitmapInfo( header, &width, &height, &planes, &bpp, &compr, &size ) == -1) return 0;
     
     if (width < 0)