[PATCH 4.9 063/164] of: fdt: add missing allocation-failure check

[Greg Kroah-Hartman]

4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Johan Hovold <johan@xxxxxxxxxx>

commit 49e67dd17649b60b4d54966e18ec9c80198227f0 upstream.

The memory allocator passed to __unflatten_device_tree() (e.g. a wrapped
kzalloc) can fail so add the missing sanity check to avoid dereferencing
a NULL pointer.

Fixes: fe14042358fa ("of/flattree: Refactor unflatten_device_tree and add fdt_unflatten_tree")
Signed-off-by: Johan Hovold <johan@xxxxxxxxxx>
Signed-off-by: Rob Herring <robh@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/of/fdt.c |    3 +++
 1 file changed, 3 insertions(+)

--- a/drivers/of/fdt.c
+++ b/drivers/of/fdt.c
@@ -505,6 +505,9 @@ static void *__unflatten_device_tree(con
 
 	/* Allocate memory for the expanded device tree */
 	mem = dt_alloc(size + 4, __alignof__(struct device_node));
+	if (!mem)
+		return NULL;
+
 	memset(mem, 0, size);
 
 	*(__be32 *)(mem + size) = cpu_to_be32(0xdeadbeef);