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From:   Aditya Pakki <pakki001@umn.edu>
To:     pakki001@umn.edu
Cc:     kjlu@umn.edu, Vishal Verma <vishal.l.verma@intel.com>,
        Dan Williams <dan.j.williams@intel.com>,
        Dave Jiang <dave.jiang@intel.com>,
        Keith Busch <keith.busch@intel.com>,
        Ira Weiny <ira.weiny@intel.com>, linux-nvdimm@lists.01.org,
        linux-kernel@vger.kernel.org
Subject: [PATCH v4] nvdimm: btt_devs: fix a NULL pointer dereference
Date:   Mon, 25 Mar 2019 16:55:27 -0500
Message-Id: <20190325215527.12574-1-pakki001@umn.edu>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

In case kmemdup fails, the fix releases resources and returns to
avoid the NULL pointer dereference.

Signed-off-by: Aditya Pakki <pakki001@umn.edu>

---
v3: Move kfree(nd_btt) to goto block.
v2: Replace incorrect kfree with ida_simple_remove, suggested by
Johannes Thumshirn
v1: Free nd_btt->id in case of failure and avoid double free, suggested
by Dan Williams
---
 drivers/nvdimm/btt_devs.c | 18 +++++++++++++-----
 1 file changed, 13 insertions(+), 5 deletions(-)

diff --git a/drivers/nvdimm/btt_devs.c b/drivers/nvdimm/btt_devs.c
index b72a303176c7..9486acc08402 100644
--- a/drivers/nvdimm/btt_devs.c
+++ b/drivers/nvdimm/btt_devs.c
@@ -198,14 +198,15 @@ static struct device *__nd_btt_create(struct nd_region *nd_region,
 		return NULL;
 
 	nd_btt->id = ida_simple_get(&nd_region->btt_ida, 0, 0, GFP_KERNEL);
-	if (nd_btt->id < 0) {
-		kfree(nd_btt);
-		return NULL;
-	}
+	if (nd_btt->id < 0)
+		goto out_nd_btt;
 
 	nd_btt->lbasize = lbasize;
-	if (uuid)
+	if (uuid) {
 		uuid = kmemdup(uuid, 16, GFP_KERNEL);
+		if (!uuid)
+			goto out_put_id;
+	}
 	nd_btt->uuid = uuid;
 	dev = &nd_btt->dev;
 	dev_set_name(dev, "btt%d.%d", nd_region->id, nd_btt->id);
@@ -220,6 +221,13 @@ static struct device *__nd_btt_create(struct nd_region *nd_region,
 		return NULL;
 	}
 	return dev;
+
+out_put_id:
+	ida_simple_remove(&nd_region->btt_ida, nd_btt->id);
+
+out_nd_btt:
+	kfree(nd_btt);
+	return NULL;
 }
 
 struct device *nd_btt_create(struct nd_region *nd_region)
-- 
2.17.1