[PATCH] afs: security: Use struct_size() in kzalloc()

From: Gustavo A. R. Silva
Date: Tue Jun 04 2019 - 12:33:33 EST

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 <gustavo@xxxxxxxxxxxxxx>
fs/afs/security.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/fs/afs/security.c b/fs/afs/security.c
index 71e71c07568f..82753f3c097f 100644
--- a/fs/afs/security.c
+++ b/fs/afs/security.c
@@ -191,8 +191,7 @@ void afs_cache_permit(struct afs_vnode *vnode, struct key *key,
* yet.
- new = kzalloc(sizeof(struct afs_permits) +
- sizeof(struct afs_permit) * size, GFP_NOFS);
+ new = kzalloc(struct_size(new, permits, size), GFP_NOFS);
if (!new)
goto out_put;