[PATCH] libnvdimm: fix NULL ptr access in nvdimm_flush when region is disabled

From: Dave Jiang <dave.jiang@intel.com>
To: dan.j.williams@intel.com
Cc: linux-nvdimm@lists.01.org
Subject: [PATCH] libnvdimm: fix NULL ptr access in nvdimm_flush when region is disabled
Date: Tue, 10 Apr 2018 13:42:38 -0700	[thread overview]
Message-ID: <152339295872.17800.11928214580818704332.stgit@djiang5-desk3.ch.intel.com> (raw)

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@intel.com>
---
 drivers/nvdimm/region_devs.c |    4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/nvdimm/region_devs.c b/drivers/nvdimm/region_devs.c
index a612be6f019d..d5619b7feb6a 100644
--- a/drivers/nvdimm/region_devs.c
+++ b/drivers/nvdimm/region_devs.c
@@ -1074,6 +1074,10 @@ void nvdimm_flush(struct nd_region *nd_region)
 	struct nd_region_data *ndrd = dev_get_drvdata(&nd_region->dev);
 	int i, idx;
 
+	/* protect against disabled region */
+	if (!nd_region->dev.driver)
+		return;
+
 	/*
 	 * Try to encourage some diversity in flush hint addresses
 	 * across cpus assuming a limited number of flush hints.

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