From a462903fa22541f212134fba81084315ad843e6e Mon Sep 17 00:00:00 2001 From: Johannes Berg Date: Fri, 16 May 2025 13:59:27 +0200 Subject: [PATCH] net: netlink: reduce extack cookie size Seems like the extack cookie hasn't found any users outside of wireless, which always uses nl_set_extack_cookie_u64(). Thus, allocating 20 bytes for it is pointless, reduce that to 8 bytes, and add a BUILD_BUG_ON() to ensure it's enough (obviously it is, for a u64, but in case it changes again.) Signed-off-by: Johannes Berg Link: https://patch.msgid.link/20250516115927.38209-2-johannes@sipsolutions.net Signed-off-by: Jakub Kicinski --- include/linux/netlink.h | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/include/linux/netlink.h b/include/linux/netlink.h index c3ae84a77e16..882e9c1b6c1d 100644 --- a/include/linux/netlink.h +++ b/include/linux/netlink.h @@ -63,7 +63,7 @@ netlink_kernel_create(struct net *net, int unit, struct netlink_kernel_cfg *cfg) } /* this can be increased when necessary - don't expose to userland */ -#define NETLINK_MAX_COOKIE_LEN 20 +#define NETLINK_MAX_COOKIE_LEN 8 #define NETLINK_MAX_FMTMSG_LEN 80 /** @@ -212,6 +212,7 @@ static inline void nl_set_extack_cookie_u64(struct netlink_ext_ack *extack, { if (!extack) return; + BUILD_BUG_ON(sizeof(extack->cookie) < sizeof(cookie)); memcpy(extack->cookie, &cookie, sizeof(cookie)); extack->cookie_len = sizeof(cookie); } -- 2.25.1