arm64: kexec_file: fix memory leakage in create_dtb() when fdt_open_into() fails

arm64: kexec_file: fix memory leakage in create_dtb() when fdt_open_into() fails

commit 656d1d58d8e0958d372db86c24f0b2ea36f50888 upstream.

in function create_dtb(), if fdt_open_into() fails, we need to vfree
buf before return.

Fixes: 52b2a8af7436 ("arm64: kexec_file: load initrd and device-tree")
Cc: stable@vger.kernel.org # v5.0
Signed-off-by: qiuguorui1 <qiuguorui1@huawei.com>
Link: https://lore.kernel.org/r/20210218125900.6810-1-qiuguorui1@huawei.com
Signed-off-by: Will Deacon <will@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>