linux-kernel - [PATCH] ovl: Replace offsetof() with struct_size() in ovl_stack

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Message-ID: <20250503103415.281123-2-thorsten.blum@linux.dev>
Date: Sat,  3 May 2025 12:34:16 +0200
From: Thorsten Blum <thorsten.blum@...ux.dev>
To: Miklos Szeredi <miklos@...redi.hu>,
	Amir Goldstein <amir73il@...il.com>
Cc: Thorsten Blum <thorsten.blum@...ux.dev>,
	linux-unionfs@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH] ovl: Replace offsetof() with struct_size() in ovl_stack_free()

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@...ux.dev>
---
 fs/overlayfs/util.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/fs/overlayfs/util.c b/fs/overlayfs/util.c
index 0819c739cc2f..dea0df3272e3 100644
--- a/fs/overlayfs/util.c
+++ b/fs/overlayfs/util.c
@@ -145,9 +145,9 @@ void ovl_stack_free(struct ovl_path *stack, unsigned int n)
 
 struct ovl_entry *ovl_alloc_entry(unsigned int numlower)
 {
-	size_t size = offsetof(struct ovl_entry, __lowerstack[numlower]);
-	struct ovl_entry *oe = kzalloc(size, GFP_KERNEL);
+	struct ovl_entry *oe;
 
+	oe = kzalloc(struct_size(oe, __lowerstack, numlower), GFP_KERNEL);
 	if (oe)
 		oe->__numlower = numlower;
 
-- 
2.49.0