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Benson Leung authored
The put_device(dev) at the bottom of the loop of device_shutdown may result in the dev being cleaned up. In device_create_release, the dev is kfreed. However, device_shutdown attempts to use the dev pointer again after put_device by referring to dev->parent. Copy the parent pointer instead to avoid this condition. This bug was found on Chromium OS's chromeos-3.8, which is based on v3.8.11. See bug report : https://code.google.com/p/chromium/issues/detail?id=297842 This can easily be reproduced when shutting down with hidraw devices that report battery condition. Two examples are the HP Bluetooth Mouse X4000b and the Apple Magic Mouse. For example, with the magic mouse : The dev in question is "hidraw0" dev->parent is "magicmouse" In the course of the shutdown for this device, the input event cleanup calls a put on hidraw0, decrementing its reference count. When we finally get to put_device(dev) in device_shutdown, kobject_cleanup is called and device_create_release does kfree(dev). dev->parent is no longer valid, and we may crash in put_device(dev->parent). This change should be applied on any kernel with this change : d1c6c030 Cc: stable@vger.kernel.org Signed-off-by:
Benson Leung <bleung@chromium.org> Reviewed-by:
Ming Lei <ming.lei@canonical.com> Signed-off-by:
Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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