commit b7d698d7 upstream.

mem->start is a long, so this can overflow on 32bit systems.
Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Jammy Zhou <Jammy.Zhou@amd.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>