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    Subject[PATCH 4.11 045/114] IB/core: Fix sysfs registration error flow
    Date
    4.11-stable review patch.  If anyone has any objections, please let me know.

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

    From: Jack Morgenstein <jackm@dev.mellanox.co.il>

    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")
    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: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    drivers/infiniband/core/sysfs.c | 2 +-
    1 file changed, 1 insertion(+), 1 deletion(-)

    --- 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;

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