[PATCH net-next v2 2/2] KEYS: annotate struct user_key_payload with __counted_by

Thorsten Blum
2026-04-09T22:58:26Z

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

Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
---
Changes in v2:
- Use __aligned(8) as suggested by David
- v1: https://lore.kernel.org/lkml/20260409073711.57020-6-thorsten.blum@linux.dev/

Cc: netdev@vger.kernel.org
---
include/keys/user-type.h | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/include/keys/user-type.h b/include/keys/user-type.h
index 386c31432789..c29ed9f5d300 100644
--- a/include/keys/user-type.h
+++ b/include/keys/user-type.h
@@ -27,7 +27,8 @@
struct user_key_payload {
struct rcu_head rcu; /* RCU destructor */
unsigned short datalen; /* length of this data */
- char data[] __aligned(__alignof__(u64)); /* actual data */
+ char data[] /* actual data */
+ __aligned(8) __counted_by(datalen);
};

extern struct key_type key_type_user;