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

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

Fixes: 52b2a8af ("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.comSigned-off-by: Will Deacon <will@kernel.org>

arch/arm64/kernel/machine_kexec_file.c

@@ -182,8 +182,10 @@ static int create_dtb(struct kimage *image,
 
 		/* duplicate a device tree blob */
 		ret = fdt_open_into(initial_boot_params, buf, buf_size);
-		if (ret)
+		if (ret) {
+			vfree(buf);
 			return -EINVAL;
+		}
 
 		ret = setup_dtb(image, initrd_load_addr, initrd_len,
 				cmdline, buf);