[PATCH] ovl: Annotate struct ovl_entry with __counted_by()

From: Thorsten Blum
Date: Sat May 03 2025 - 09:26:43 EST


Add the __counted_by() compiler attribute to the flexible array member
'__lowerstack' to improve access bounds-checking via CONFIG_UBSAN_BOUNDS
and CONFIG_FORTIFY_SOURCE.

Signed-off-by: Thorsten Blum <thorsten.blum@xxxxxxxxx>
---
fs/overlayfs/ovl_entry.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/overlayfs/ovl_entry.h b/fs/overlayfs/ovl_entry.h
index cb449ab310a7..afb7762f873f 100644
--- a/fs/overlayfs/ovl_entry.h
+++ b/fs/overlayfs/ovl_entry.h
@@ -51,7 +51,7 @@ struct ovl_path {

struct ovl_entry {
unsigned int __numlower;
- struct ovl_path __lowerstack[];
+ struct ovl_path __lowerstack[] __counted_by(__numlower);
};

/* private information held for overlayfs's superblock */
--
2.49.0