From: Gustavo A. R. Silva <gustavo@embeddedor.com>
Date: Mon, 10 Jun 2019 21:06:13 +0000 (-0500)
Subject: libnvdimm, region: Use struct_size() in kzalloc()
X-Git-Tag: microblaze-v5.5-rc1~39^2~17
X-Git-Url: http://git.monstr.eu/?p=linux-2.6-microblaze.git;a=commitdiff_plain;h=2b90cb223320a93b1be6c2616efe6f9ff14d8b28

libnvdimm, region: Use struct_size() in kzalloc()

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>
Reviewed-by: Vishal Verma <vishal.l.verma@intel.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20190610210613.GA21989@embeddedor
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---

diff --git a/drivers/nvdimm/region_devs.c b/drivers/nvdimm/region_devs.c
index af30cbe7a8ea..b477a8dc0020 100644
--- a/drivers/nvdimm/region_devs.c
+++ b/drivers/nvdimm/region_devs.c
@@ -1025,10 +1025,9 @@ 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;
 	}