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

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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>
This commit is contained in:
Jeremy Kerr 2025-05-21 17:33:36 +08:00 committed by Paolo Abeni
parent 31eaaa5cb5
commit 0a9b2c9fd1
2 changed files with 6 additions and 3 deletions
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4
net/mctp/device.c
View File

@ -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) {

5
net/mctp/neigh.c
View File

@ -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;