From 031b558dfe13d222f4c5468ba81b9eb84a62ffb7 Mon Sep 17 00:00:00 2001
From: Jack Morgenstein <jackm@dev.mellanox.co.il>
Date: Sun, 19 Mar 2017 10:55:57 +0200
Subject: [PATCH] IB/core: Fix sysfs registration error flow

commit b312be3d87e4c80872cbea869e569175c5eb0f9a upstream.

The kernel commit cited below restructured ib device management
so that the device kobject is initialized in ib_alloc_device.

As part of the restructuring, the kobject is now initialized in
procedure ib_alloc_device, and is later added to the device hierarchy
in the ib_register_device call stack, in procedure
ib_device_register_sysfs (which calls device_add).

However, in the ib_device_register_sysfs error flow, if an error
occurs following the call to device_add, the cleanup procedure
device_unregister is called. This call results in the device object
being deleted -- which results in various use-after-free crashes.

The correct cleanup call is device_del -- which undoes device_add
without deleting the device object.

The device object will then (correctly) be deleted in the
ib_register_device caller's error cleanup flow, when the caller invokes
ib_dealloc_device.

Fixes: 55aeed06544f6 ("IB/core: Make ib_alloc_device init the kobject")
Cc: <stable@vger.kernel.org> # v4.2+
Signed-off-by: Jack Morgenstein <jackm@dev.mellanox.co.il>
Signed-off-by: Leon Romanovsky <leon@kernel.org>
Signed-off-by: Doug Ledford <dledford@redhat.com>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>

diff --git a/drivers/infiniband/core/sysfs.c b/drivers/infiniband/core/sysfs.c
index 15defefecb4f..115f68cd914d 100644
--- a/drivers/infiniband/core/sysfs.c
+++ b/drivers/infiniband/core/sysfs.c
@@ -1301,7 +1301,7 @@ err_put:
 	free_port_list_attributes(device);
 
 err_unregister:
-	device_unregister(class_dev);
+	device_del(class_dev);
 
 err:
 	return ret;
-- 
2.12.0