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* [PATCH] ima: ima_api: Use struct_size() in kzalloc()
@ 2019-08-29 17:29 Gustavo A. R. Silva
  0 siblings, 0 replies; only message in thread
From: Gustavo A. R. Silva @ 2019-08-29 17:29 UTC (permalink / raw)
  To: Mimi Zohar, Dmitry Kasatkin, James Morris, Serge E. Hallyn
  Cc: linux-integrity, linux-security-module, linux-kernel,
	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 ima_template_entry {
        struct ima_field_data template_data[0]; /* template related data */

instance = kzalloc(sizeof(struct ima_template_entry) + count * sizeof(struct ima_field_data), GFP_NOFS);

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_NOFS);

This code was detected with the help of Coccinelle.

Signed-off-by: Gustavo A. R. Silva <>
 security/integrity/ima/ima_api.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/security/integrity/ima/ima_api.c b/security/integrity/ima/ima_api.c
index 65224474675b..610759fe63b8 100644
--- a/security/integrity/ima/ima_api.c
+++ b/security/integrity/ima/ima_api.c
@@ -45,8 +45,8 @@ int ima_alloc_init_template(struct ima_event_data *event_data,
 		template_desc = ima_template_desc_current();
-	*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;

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2019-08-29 17:29 [PATCH] ima: ima_api: Use struct_size() in kzalloc() Gustavo A. R. Silva

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