[PATCH v2] of: unflatten_and_copy: handle NULL initial_boot_params

From: James Hogan
Date: Thu Nov 21 2013 - 08:45:36 EST


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. In this case also log a warning for when the kernel log buffer is
obtainable.

Signed-off-by: James Hogan <james.hogan@xxxxxxxxxx>
Cc: Grant Likely <grant.likely@xxxxxxxxxx>
Cc: Rob Herring <rob.herring@xxxxxxxxxxx>
Cc: devicetree@xxxxxxxxxxxxxxx
Cc: linux-arch@xxxxxxxxxxxxxxx
---
v2:
* Log a warning for those who can obtain the kernel log buffer (Grant
Likely).
---
drivers/of/fdt.c | 12 ++++++++++--
1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
index 2fa024b97c43..758b4f8b30b7 100644
--- a/drivers/of/fdt.c
+++ b/drivers/of/fdt.c
@@ -922,8 +922,16 @@ 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) {
+ pr_warn("No valid device tree found, continuing without\n");
+ 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


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