Driver core expects devices to be dynamically allocated and will, for
example, complain loudly if a device that lacks a release function is
ever freed.

Use root_device_register() to allocate and register the root device
instead of open coding using a static device.

Also add the missing sanity check when registering ibmebus devices to
avoid use-after-free if the bus failed to register (which would
previously have triggered a bunch of use-after-free warnings).

Signed-off-by: Johan Hovold <[email protected]>
---
 arch/powerpc/platforms/pseries/ibmebus.c | 39 ++++++++++++++----------
 1 file changed, 23 insertions(+), 16 deletions(-)

diff --git a/arch/powerpc/platforms/pseries/ibmebus.c 
b/arch/powerpc/platforms/pseries/ibmebus.c
index 2d0f991da2c8..48076fe6ab30 100644
--- a/arch/powerpc/platforms/pseries/ibmebus.c
+++ b/arch/powerpc/platforms/pseries/ibmebus.c
@@ -52,9 +52,7 @@
 #include <asm/ibmebus.h>
 #include <asm/machdep.h>
 
-static struct device ibmebus_bus_device = { /* fake "parent" device */
-       .init_name = "ibmebus",
-};
+static struct device *ibmebus_bus_device;      /* fake "parent" device */
 
 const struct bus_type ibmebus_bus_type;
 
@@ -172,7 +170,10 @@ static int ibmebus_create_device(struct device_node *dn)
        struct platform_device *dev;
        int ret;
 
-       dev = of_device_alloc(dn, NULL, &ibmebus_bus_device);
+       if (!ibmebus_bus_device)
+               return -ENOENT;
+
+       dev = of_device_alloc(dn, NULL, ibmebus_bus_device);
        if (!dev)
                return -ENOMEM;
 
@@ -448,6 +449,7 @@ EXPORT_SYMBOL(ibmebus_bus_type);
 
 static int __init ibmebus_bus_init(void)
 {
+       struct device *root;
        int err;
 
        printk(KERN_INFO "IBM eBus Device Driver\n");
@@ -459,23 +461,28 @@ static int __init ibmebus_bus_init(void)
                return err;
        }
 
-       err = device_register(&ibmebus_bus_device);
-       if (err) {
-               printk(KERN_WARNING "%s: device_register returned %i\n",
+       root = root_device_register("ibmebus");
+       if (IS_ERR(root)) {
+               err = PTR_ERR(root);
+               printk(KERN_WARNING "%s: root_device_register returned %i\n",
                       __func__, err);
-               put_device(&ibmebus_bus_device);
-               bus_unregister(&ibmebus_bus_type);
-
-               return err;
+               goto err_deregister_bus;
        }
 
+       ibmebus_bus_device = root;
+
        err = ibmebus_create_devices(ibmebus_matches);
-       if (err) {
-               device_unregister(&ibmebus_bus_device);
-               bus_unregister(&ibmebus_bus_type);
-               return err;
-       }
+       if (err)
+               goto err_deregister_root;
 
        return 0;
+
+err_deregister_root:
+       ibmebus_bus_device = NULL;
+       root_device_unregister(root);
+err_deregister_bus:
+       bus_unregister(&ibmebus_bus_type);
+
+       return err;
 }
 machine_postcore_initcall(pseries, ibmebus_bus_init);
-- 
2.54.0


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