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From: "Gustavo A. R. Silva" <gustavo@embeddedor.com>
To: Dan Williams <dan.j.williams@intel.com>,
	Vishal Verma <vishal.l.verma@intel.com>,
	Dave Jiang <dave.jiang@intel.com>,
	Keith Busch <keith.busch@intel.com>,
	Ira Weiny <ira.weiny@intel.com>
Cc: "Gustavo A. R. Silva" <gustavo@embeddedor.com>,
	linux-kernel@vger.kernel.org, linux-nvdimm@lists.01.org
Subject: [PATCH] libnvdimm, region: Use struct_size() in kzalloc()
Date: Mon, 10 Jun 2019 16:06:13 -0500	[thread overview]
Message-ID: <20190610210613.GA21989@embeddedor> (raw)

One of the more common cases of allocation size calculations is finding
the size of a structure that has a zero-sized array at the end, along
with memory for some number of elements for that array. For example:

struct nd_region {
	...
        struct nd_mapping mapping[0];
};

instance = kzalloc(sizeof(struct nd_region) + sizeof(struct nd_mapping) *
                          count, GFP_KERNEL);

Instead of leaving these open-coded and prone to type mistakes, we can
now use the new struct_size() helper:

instance = kzalloc(struct_size(instance, mapping, count), GFP_KERNEL);

This code was detected with the help of Coccinelle.

Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
---
 drivers/nvdimm/region_devs.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/drivers/nvdimm/region_devs.c b/drivers/nvdimm/region_devs.c
index b4ef7d9ff22e..88becc87e234 100644
--- a/drivers/nvdimm/region_devs.c
+++ b/drivers/nvdimm/region_devs.c
@@ -1027,10 +1027,9 @@ static struct nd_region *nd_region_create(struct nvdimm_bus *nvdimm_bus,
 		}
 		region_buf = ndbr;
 	} else {
-		nd_region = kzalloc(sizeof(struct nd_region)
-				+ sizeof(struct nd_mapping)
-				* ndr_desc->num_mappings,
-				GFP_KERNEL);
+		nd_region = kzalloc(struct_size(nd_region, mapping,
+						ndr_desc->num_mappings),
+				    GFP_KERNEL);
 		region_buf = nd_region;
 	}
 
-- 
2.21.0

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Linux-nvdimm@lists.01.org
https://lists.01.org/mailman/listinfo/linux-nvdimm

WARNING: multiple messages have this Message-ID (diff)
From: "Gustavo A. R. Silva" <gustavo@embeddedor.com>
To: Dan Williams <dan.j.williams@intel.com>,
	Vishal Verma <vishal.l.verma@intel.com>,
	Dave Jiang <dave.jiang@intel.com>,
	Keith Busch <keith.busch@intel.com>,
	Ira Weiny <ira.weiny@intel.com>
Cc: linux-nvdimm@lists.01.org, linux-kernel@vger.kernel.org,
	"Gustavo A. R. Silva" <gustavo@embeddedor.com>
Subject: [PATCH] libnvdimm, region: Use struct_size() in kzalloc()
Date: Mon, 10 Jun 2019 16:06:13 -0500	[thread overview]
Message-ID: <20190610210613.GA21989@embeddedor> (raw)

One of the more common cases of allocation size calculations is finding
the size of a structure that has a zero-sized array at the end, along
with memory for some number of elements for that array. For example:

struct nd_region {
	...
        struct nd_mapping mapping[0];
};

instance = kzalloc(sizeof(struct nd_region) + sizeof(struct nd_mapping) *
                          count, GFP_KERNEL);

Instead of leaving these open-coded and prone to type mistakes, we can
now use the new struct_size() helper:

instance = kzalloc(struct_size(instance, mapping, count), GFP_KERNEL);

This code was detected with the help of Coccinelle.

Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
---
 drivers/nvdimm/region_devs.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/drivers/nvdimm/region_devs.c b/drivers/nvdimm/region_devs.c
index b4ef7d9ff22e..88becc87e234 100644
--- a/drivers/nvdimm/region_devs.c
+++ b/drivers/nvdimm/region_devs.c
@@ -1027,10 +1027,9 @@ static struct nd_region *nd_region_create(struct nvdimm_bus *nvdimm_bus,
 		}
 		region_buf = ndbr;
 	} else {
-		nd_region = kzalloc(sizeof(struct nd_region)
-				+ sizeof(struct nd_mapping)
-				* ndr_desc->num_mappings,
-				GFP_KERNEL);
+		nd_region = kzalloc(struct_size(nd_region, mapping,
+						ndr_desc->num_mappings),
+				    GFP_KERNEL);
 		region_buf = nd_region;
 	}
 
-- 
2.21.0


             reply	other threads:[~2019-06-10 21:06 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-06-10 21:06 Gustavo A. R. Silva [this message]
2019-06-10 21:06 ` [PATCH] libnvdimm, region: Use struct_size() in kzalloc() Gustavo A. R. Silva
2019-08-28 18:30 ` Gustavo A. R. Silva
2019-08-28 18:30   ` Gustavo A. R. Silva
2019-08-28 20:25   ` Kees Cook
2019-08-28 20:25     ` Kees Cook
2019-08-28 18:51 ` Verma, Vishal L
2019-08-28 18:51   ` Verma, Vishal L
2019-08-28 19:36   ` Gustavo A. R. Silva
2019-08-28 19:36     ` Gustavo A. R. Silva
2019-08-28 20:24     ` Verma, Vishal L
2019-08-28 20:24       ` Verma, Vishal L
2019-08-29 21:04       ` Dan Williams
2019-08-29 21:04         ` Dan Williams
  -- strict thread matches above, loose matches on Subject: below --
2019-02-21 15:23 [PATCH] libnvdimm, region: use " Gustavo A. R. Silva

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