When a region is disabled, there is no driver attached. Therefore dev->driverdata is NULL. An attempt to write to regionN/deep_flush via sysfs would cause a NULL pointer dereference. Bail when dev->driver is NULL to protect this scenario. Fix: ab630891ce0eb(libnvdimm, region: sysfs trigger for nvdimm_flush()) Signed-off-by: Dave Jiang <dave.jiang(a)intel.com&gt; --- v2: Move to deep_flush_store. (Dan) drivers/nvdimm/region_devs.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/drivers/nvdimm/region_devs.c b/drivers/nvdimm/region_devs.c index a612be6f019d..65cc2a5b48b8 100644 --- a/drivers/nvdimm/region_devs.c +++ b/drivers/nvdimm/region_devs.c @@ -290,6 +290,11 @@ static ssize_t deep_flush_store(struct device *dev, struct device_attribute *att return rc; if (!flush) return -EINVAL; + + /* protect against disabled region */ + if (!nd_region->dev.driver) + return -ENXIO; + nvdimm_flush(nd_region); return len;