Subject: [PATCH net-next v3 2/2] KEYS: annotate struct user_key_payload with __counted_by

From: Thorsten Blum <[email-masked]>
Date: Mon, 27 Apr 2026 13:44:24 +0200

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

Signed-off-by: Thorsten Blum <[email-masked]>
---
Changes in v3:
- Formatting only, do not split the declaration into two lines (Jarkko)
- v2: https://lore.kernel.org/lkml/[email-masked]/

Changes in v2:
- Use __aligned(8) as suggested by David
- v1: https://lore.kernel.org/lkml/[email-masked]/
---
 include/keys/user-type.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/keys/user-type.h b/include/keys/user-type.h
index 386c31432789..30de4f92a721 100644
--- a/include/keys/user-type.h
+++ b/include/keys/user-type.h
@@ -27,7 +27,7 @@
 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[] __aligned(8) __counted_by(datalen); /* actual data */
 };
 
 extern struct key_type key_type_user;