of/flattree: Fix crash when device tree absent

This patch fixes the condition where device tree support is compiled
in, but no device tree was proved by firmware.  It makes
of_platform_bus_probe() explicitly check for a NULL device tree
pointer.

Signed-off-by: Grant Likely <grant.likely@secretlab.ca>

1 files changed, 2 insertions, 0 deletions

diff --git a/drivers/of/platform.c b/drivers/of/platform.c
index 5be008035b94..c52a798684a9 100644
--- a/drivers/of/platform.c
+++ b/drivers/of/platform.c
@@ -617,6 +617,8 @@ int of_platform_bus_probe(struct device_node *root,
                 root = of_find_node_by_path("/");
         else
                 of_node_get(root);
+        if (root == NULL)
+                return -EINVAL;
 
         pr_debug("of_platform_bus_probe()\n");
         pr_debug(" starting at: %s\n", root->full_name);