[PATCH] bootconfig: Fix to check the xbc_node is used before free it

[Masami Hiramatsu]

Fix to check the xbc_node is used before calling memblock_free()
because passing NULL to phys_addr() will cause a panic.
This will happen if user doesn't pass any bootconfig to the
kernel, because kernel will call xbc_destroy_all() after
booting.

Fixes: 40caa127f3c7 ("init: bootconfig: Remove all bootconfig data when the init memory is removed")
Reported-by: kernel test robot <oliver.sang@xxxxxxxxx>
Signed-off-by: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
---
 lib/bootconfig.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/lib/bootconfig.c b/lib/bootconfig.c
index f8419cff1147..4f8849706ef6 100644
--- a/lib/bootconfig.c
+++ b/lib/bootconfig.c
@@ -792,7 +792,8 @@ void __init xbc_destroy_all(void)
 	xbc_data = NULL;
 	xbc_data_size = 0;
 	xbc_node_num = 0;
-	memblock_free(__pa(xbc_nodes), sizeof(struct xbc_node) * XBC_NODE_MAX);
+	if (xbc_nodes)
+		memblock_free(__pa(xbc_nodes), sizeof(struct xbc_node) * XBC_NODE_MAX);
 	xbc_nodes = NULL;
 	brace_index = 0;
 }