[PATCH] of: unflatten_and_copy: handle NULL initial_boot_params

[James Hogan <james.hogan@imgtec.com>]

Check whether initial_boot_params is NULL before dereferencing it in
unflatten_and_copy_device_tree() for the case where no device tree is
available but the arch can still boot to a minimal usable system without
it.

Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Grant Likely <grant.likely@linaro.org>
Cc: Rob Herring <rob.herring@calxeda.com>
Cc: devicetree@vger.kernel.org
Cc: linux-arch@vger.kernel.org
---
 drivers/of/fdt.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
index 2fa024b97c43..ac4983955e6d 100644
--- a/drivers/of/fdt.c
+++ b/drivers/of/fdt.c
@@ -922,8 +922,14 @@ void __init unflatten_device_tree(void)
  */
 void __init unflatten_and_copy_device_tree(void)
 {
-	int size = __be32_to_cpu(initial_boot_params->totalsize);
-	void *dt = early_init_dt_alloc_memory_arch(size,
+	int size;
+	void *dt;
+
+	if (!initial_boot_params)
+		return;
+
+	size = __be32_to_cpu(initial_boot_params->totalsize);
+	dt = early_init_dt_alloc_memory_arch(size,
 		__alignof__(struct boot_param_header));
 
 	if (dt) {
-- 
1.8.1.2