grub-core/loader/efi/fdt.c: Do not copy random memory

We should not try to copy any memory area which is outside of the original
fdt. If this extra memory is controlled by a hypervisor this might end
with a crash.

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Reviewed-by: Leif Lindholm <leif.lindholm@linaro.org>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>

grub-core/loader/efi/fdt.c

@@ -66,7 +66,7 @@ grub_fdt_load (grub_size_t additional_size)
 
   if (raw_fdt)
     {
-      grub_memmove (fdt, raw_fdt, size);
+      grub_memmove (fdt, raw_fdt, size - additional_size);
       grub_fdt_set_totalsize (fdt, size);
     }
   else