From ff81d1c77d0890b0cf835378614ba6df02de6cd8 Mon Sep 17 00:00:00 2001 From: Jakub Kicinski Date: Thu, 17 Nov 2022 19:39:03 -0800 Subject: [PATCH] netlink: remove the flex array from struct nlmsghdr commit c73a72f4cbb47672c8cc7f7d7aba52f1cb15baca upstream. I've added a flex array to struct nlmsghdr in commit 738136a0e375 ("netlink: split up copies in the ack construction") to allow accessing the data easily. It leads to warnings with clang, if user space wraps this structure into another struct and the flex array is not at the end of the container. Reviewed-by: Kees Cook Reviewed-by: David Ahern Link: https://lore.kernel.org/all/20221114023927.GA685@u2004-local/ Link: https://lore.kernel.org/r/20221118033903.1651026-1-kuba@kernel.org Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman --- include/uapi/linux/netlink.h | 2 -- net/netlink/af_netlink.c | 2 +- 2 files changed, 1 insertion(+), 3 deletions(-) diff --git a/include/uapi/linux/netlink.h b/include/uapi/linux/netlink.h index 5da0da59bf010..e2ae82e3f9f71 100644 --- a/include/uapi/linux/netlink.h +++ b/include/uapi/linux/netlink.h @@ -48,7 +48,6 @@ struct sockaddr_nl { * @nlmsg_flags: Additional flags * @nlmsg_seq: Sequence number * @nlmsg_pid: Sending process port ID - * @nlmsg_data: Message payload */ struct nlmsghdr { __u32 nlmsg_len; @@ -56,7 +55,6 @@ struct nlmsghdr { __u16 nlmsg_flags; __u32 nlmsg_seq; __u32 nlmsg_pid; - __u8 nlmsg_data[]; }; /* Flags values */ diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c index a572a30dfd98d..cb833302270a6 100644 --- a/net/netlink/af_netlink.c +++ b/net/netlink/af_netlink.c @@ -2458,7 +2458,7 @@ void netlink_ack(struct sk_buff *in_skb, struct nlmsghdr *nlh, int err, if (!nlmsg_append(skb, nlmsg_len(nlh))) goto err_bad_put; - memcpy(errmsg->msg.nlmsg_data, nlh->nlmsg_data, + memcpy(nlmsg_data(&errmsg->msg), nlmsg_data(nlh), nlmsg_len(nlh)); } -- 2.39.5