linux-kernel - [PATCH] posix_acl: Use struct

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Date:   Thu, 2 May 2019 11:57:33 -0500
From:   "Gustavo A. R. Silva" <gustavo@...eddedor.com>
To:     Alexander Viro <viro@...iv.linux.org.uk>
Cc:     linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
        "Gustavo A. R. Silva" <gustavo@...eddedor.com>
Subject: [PATCH] posix_acl: Use struct_size() helper

Make use of the struct_size() helper instead of an open-coded version
in order to avoid any potential type mistakes, in particular in the
context in which this code is being used.

So, replace code of the following form:

sizeof(struct posix_acl) + count * sizeof(struct posix_acl_entry)

with:

struct_size(acl, a_entries, count)

and so on...

Notice that variable size is unnecessary, hence it is removed.

This code was detected with the help of Coccinelle.

Signed-off-by: Gustavo A. R. Silva <gustavo@...eddedor.com>
---
 fs/posix_acl.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/fs/posix_acl.c b/fs/posix_acl.c
index 2fd0fde16fe1..d654d8f87280 100644
--- a/fs/posix_acl.c
+++ b/fs/posix_acl.c
@@ -175,9 +175,9 @@ EXPORT_SYMBOL(posix_acl_init);
 struct posix_acl *
 posix_acl_alloc(int count, gfp_t flags)
 {
-	const size_t size = sizeof(struct posix_acl) +
-	                    count * sizeof(struct posix_acl_entry);
-	struct posix_acl *acl = kmalloc(size, flags);
+	struct posix_acl *acl;
+
+	acl = kmalloc(struct_size(acl, a_entries, count), flags);
 	if (acl)
 		posix_acl_init(acl, count);
 	return acl;
@@ -193,9 +193,9 @@ posix_acl_clone(const struct posix_acl *acl, gfp_t flags)
 	struct posix_acl *clone = NULL;
 
 	if (acl) {
-		int size = sizeof(struct posix_acl) + acl->a_count *
-		           sizeof(struct posix_acl_entry);
-		clone = kmemdup(acl, size, flags);
+		clone = kmemdup(acl,
+				struct_size(clone, a_entries, acl->a_count),
+				flags);
 		if (clone)
 			refcount_set(&clone->a_refcount, 1);
 	}
-- 
2.21.0