From: Thorsten Blum <thorsten.blum@linux.dev>
Date: Sat, 3 May 2025 11:52:44 +0000 (+0200)
Subject: ovl: Replace offsetof() with struct_size() in ovl_stack_free()
X-Git-Tag: v6.16-rc1~22^2~1
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=7314166ee7592513c77cfbb8ff579f376039f9c4;p=thirdparty%2Fkernel%2Flinux.git

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@linux.dev>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
---

diff --git a/fs/overlayfs/util.c b/fs/overlayfs/util.c
index 5d6b60d56c275..dcccb4b4a66c7 100644
--- a/fs/overlayfs/util.c
+++ b/fs/overlayfs/util.c
@@ -15,6 +15,7 @@
 #include <linux/uuid.h>
 #include <linux/namei.h>
 #include <linux/ratelimit.h>
+#include <linux/overflow.h>
 #include "overlayfs.h"
 
 /* Get write access to upper mnt - may fail if upper sb was remounted ro */
@@ -145,9 +146,9 @@ 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;