[PATCH] ima: use struct_size() in kzalloc()

[Gustavo A. R. Silva]

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 foo {
   int stuff;
   struct boo entry[];
};

instance = kzalloc(sizeof(struct foo) + count * sizeof(struct boo), 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, entry, count), GFP_KERNEL);

This code was detected with the help of Coccinelle.

Signed-off-by: Gustavo A. R. Silva <gust...@embeddedor.com>
---
 security/integrity/ima/ima_template.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/security/integrity/ima/ima_template.c 
b/security/integrity/ima/ima_template.c
index b631b8bc7624..b945dff2ed14 100644
--- a/security/integrity/ima/ima_template.c
+++ b/security/integrity/ima/ima_template.c
@@ -281,9 +281,8 @@ static int ima_restore_template_data(struct 
ima_template_desc *template_desc,
        int ret = 0;
        int i;
 
-       *entry = kzalloc(sizeof(**entry) +
-                   template_desc->num_fields * sizeof(struct ima_field_data),
-                   GFP_NOFS);
+       *entry = kzalloc(struct_size(*entry, template_data,
+                                    template_desc->num_fields), GFP_NOFS);
        if (!*entry)
                return -ENOMEM;
 
-- 
2.21.0