firmware: arm_scmi: Avoid double free in error flow

If device_register() fails, both put_device() and kfree() are called,
ending with a double free of the scmi_dev.

Calling kfree() is needed only when a failure happens between the
allocation of the scmi_dev and its registration, so move it to there
and remove it from the error flow.

Fixes: 46edb8d1 ("firmware: arm_scmi: provide the mandatory device release callback")
Signed-off-by: Wen Yang <wenyang@linux.alibaba.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

drivers/firmware/arm_scmi/bus.c

@@ -135,8 +135,10 @@ scmi_device_create(struct device_node *np, struct device *parent, int protocol)
 		return NULL;
 
 	id = ida_simple_get(&scmi_bus_id, 1, 0, GFP_KERNEL);
-	if (id < 0)
-		goto free_mem;
+	if (id < 0) {
+		kfree(scmi_dev);
+		return NULL;
+	}
 
 	scmi_dev->id = id;
 	scmi_dev->protocol_id = protocol;
@@ -154,8 +156,6 @@ scmi_device_create(struct device_node *np, struct device *parent, int protocol)
 put_dev:
 	put_device(&scmi_dev->dev);
 	ida_simple_remove(&scmi_bus_id, id);
-free_mem:
-	kfree(scmi_dev);
 	return NULL;
 }