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netlink: remove the flex array from struct nlmsghdr

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I've added a flex array to struct nlmsghdr in
commit 738136a0e3 ("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 <keescook@chromium.org>
Reviewed-by: David Ahern <dsahern@kernel.org>
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 <kuba@kernel.org>
This commit is contained in:
Jakub Kicinski 2022-11-17 19:39:03 -08:00
parent ab0377803d
commit c73a72f4cb
2 changed files with 1 additions and 3 deletions
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2
include/uapi/linux/netlink.h
View File

@ -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 */

2
net/netlink/af_netlink.c
View File

@ -2514,7 +2514,7 @@ 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));
}