Commit 0a9b2c9f authored May 21, 2025 by Jeremy Kerr Committed by Paolo Abeni May 26, 2025

net: mctp: use nlmsg_payload() for netlink message data extraction



Jakub suggests:

> I have a different request :) Matt, once this ends up in net-next
> (end of this week) could you refactor it to use nlmsg_payload() ?
> It doesn't exist in net but this is exactly why it was added.

This refactors the additions to both mctp_dump_addrinfo(), and
mctp_rtm_getneigh() - two cases where we're calling nlh_data() on an
an incoming netlink message, without a prior nlmsg_parse().

For the neigh.c case, we cannot hit the failure where the nlh does not
contain a full ndmsg at present, as the core handler
(net/core/neighbour.c, neigh_get()) has already validated the size
through neigh_valid_req_get(), and would have failed the get operation
before the MCTP hander is called.

However, relying on that is a bit fragile, so apply the nlmsg_payload
refector here too.

Reviewed-by: Simon Horman <horms@kernel.org>
Signed-off-by: Jeremy Kerr <jk@codeconstruct.com.au>
Link: https://patch.msgid.link/20250521-mctp-nlmsg-payload-v2-1-e85df160c405@codeconstruct.com.au


Signed-off-by: Paolo Abeni <pabeni@redhat.com>

parent 31eaaa5c

net/mctp/device.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -120,8 +120,8 @@ static int mctp_dump_addrinfo(struct sk_buff skb, struct netlink_callback cb)
		int ifindex = 0, rc;

		/* Filter by ifindex if a header is provided */
		if (cb->nlh->nlmsg_len >= nlmsg_msg_size(sizeof(*hdr))) {
		hdr = nlmsg_data(cb->nlh);
		hdr = nlmsg_payload(cb->nlh, sizeof(*hdr));
		if (hdr) {
		ifindex = hdr->ifa_index;
		} else {
		if (cb->strict_check) {

net/mctp/neigh.c

+4 −1

Original line number	Diff line number	Diff line
		@@ -250,7 +250,10 @@ static int mctp_rtm_getneigh(struct sk_buff skb, struct netlink_callback cb)
		int idx;
		} cbctx = (void )cb->ctx;

		ndmsg = nlmsg_data(cb->nlh);
		ndmsg = nlmsg_payload(cb->nlh, sizeof(*ndmsg));
		if (!ndmsg)
		return -EINVAL;

		req_ifindex = ndmsg->ndm_ifindex;

		idx = 0;