[PATCH v5 4/6] nvdimm: Fix security issue with DSM IOCTL.

Code attempts to prevent certain IOCTL DSM from being called when device is opened read only. This security feature can be trivially overcome by changing the size portion of the ioctl_command which isn't used. Check only the _IOC_NR (i.e. the command). Signed-off-by: Jerry Hoemann ---

[PATCH v5 4/6] nvdimm: Fix security issue with DSM IOCTL.

Code attempts to prevent certain IOCTL DSM from being called when device is opened read only. This security feature can be trivially overcome by changing the size portion of the ioctl_command which isn't used. Check only the _IOC_NR (i.e. the command). Signed-off-by: Jerry Hoemann