[PATCH v2] ovl: Replace offsetof() with struct_size() in ovl_cache_entry_new()

[PATCH v2] ovl: Replace offsetof() with struct_size() in ovl_cache_entry_new()

[Thorsten Blum]

Compared to offsetof(), struct_size() provides additional compile-time
checks for structs with flexible arrays (e.g., __must_be_array()).

No functional changes intended.

Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
---
Changes in v2:
- Add missing include
- Link to v1: https://lore.kernel.org/lkml/20250503091535.280888-2-thorsten.blum@linux.dev/
---
 fs/overlayfs/readdir.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/fs/overlayfs/readdir.c b/fs/overlayfs/readdir.c
index 881ec5592da5..efe4700c797e 100644
--- a/fs/overlayfs/readdir.c
+++ b/fs/overlayfs/readdir.c
@@ -13,6 +13,7 @@
 #include <linux/security.h>
 #include <linux/cred.h>
 #include <linux/ratelimit.h>
+#include <linux/overflow.h>
 #include "overlayfs.h"
 
 struct ovl_cache_entry {
@@ -147,9 +148,8 @@ static struct ovl_cache_entry *ovl_cache_entry_new(struct ovl_readdir_data *rdd,
 						   u64 ino, unsigned int d_type)
 {
 	struct ovl_cache_entry *p;
-	size_t size = offsetof(struct ovl_cache_entry, name[len + 1]);
 
-	p = kmalloc(size, GFP_KERNEL);
+	p = kmalloc(struct_size(p, name, len + 1), GFP_KERNEL);
 	if (!p)
 		return NULL;
 
-- 
2.49.0

Re: [PATCH v2] ovl: Replace offsetof() with struct_size() in ovl_cache_entry_new()

[Miklos Szeredi]

On Sat, 3 May 2025 at 13:52, Thorsten Blum <thorsten.blum@linux.dev> wrote:
>
> Compared to offsetof(), struct_size() provides additional compile-time
> checks for structs with flexible arrays (e.g., __must_be_array()).
>
> No functional changes intended.
>
> Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>

Applied, thanks.

Miklos