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

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>

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net: mctp: Ensure keys maintain only one ref to corresponding dev

mctp_flow_prepare_output() is called in mctp_route_output(), which
places outbound packets onto a given interface. The packet may re

net: mctp: Ensure keys maintain only one ref to corresponding dev

mctp_flow_prepare_output() is called in mctp_route_output(), which
places outbound packets onto a given interface. The packet may represent
a message fragment, in which case we provoke an unbalanced reference
count to the underlying device. This causes trouble if we ever attempt
to remove the interface:

[ 48.702195] usb 1-1: USB disconnect, device number 2
[ 58.883056] unregister_netdevice: waiting for mctpusb0 to become free. Usage count = 2
[ 69.022548] unregister_netdevice: waiting for mctpusb0 to become free. Usage count = 2
[ 79.172568] unregister_netdevice: waiting for mctpusb0 to become free. Usage count = 2
...

Predicate the invocation of mctp_dev_set_key() in
mctp_flow_prepare_output() on not already having associated the device
with the key. It's not yet realistic to uphold the property that the key
maintains only one device reference earlier in the transmission sequence
as the route (and therefore the device) may not be known at the time the
key is associated with the socket.

Fixes: 67737c457281 ("mctp: Pass flow data & flow release events to drivers")
Acked-by: Jeremy Kerr <jk@codeconstruct.com.au>
Signed-off-by: Andrew Jeffery <andrew@codeconstruct.com.au>
Link: https://patch.msgid.link/20250508-mctp-dev-refcount-v1-1-d4f965c67bb5@codeconstruct.com.au
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

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net: mctp: Don't access ifa_index when missing

In mctp_dump_addrinfo, ifa_index can be used to filter interfaces, but
only when the struct ifaddrmsg is provided. Otherwise it will be
comparing to un

net: mctp: Don't access ifa_index when missing

In mctp_dump_addrinfo, ifa_index can be used to filter interfaces, but
only when the struct ifaddrmsg is provided. Otherwise it will be
comparing to uninitialised memory - reproducible in the syzkaller case from
dhcpd, or busybox "ip addr show".

The kernel MCTP implementation has always filtered by ifa_index, so
existing userspace programs expecting to dump MCTP addresses must
already be passing a valid ifa_index value (either 0 or a real index).

BUG: KMSAN: uninit-value in mctp_dump_addrinfo+0x208/0xac0 net/mctp/device.c:128
mctp_dump_addrinfo+0x208/0xac0 net/mctp/device.c:128
rtnl_dump_all+0x3ec/0x5b0 net/core/rtnetlink.c:4380
rtnl_dumpit+0xd5/0x2f0 net/core/rtnetlink.c:6824
netlink_dump+0x97b/0x1690 net/netlink/af_netlink.c:2309

Fixes: 583be982d934 ("mctp: Add device handling and netlink interface")
Reported-by: syzbot+e76d52dadc089b9d197f@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/all/68135815.050a0220.3a872c.000e.GAE@google.com/
Reported-by: syzbot+1065a199625a388fce60@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/all/681357d6.050a0220.14dd7d.000d.GAE@google.com/
Signed-off-by: Matt Johnston <matt@codeconstruct.com.au>
Link: https://patch.msgid.link/20250508-mctp-addr-dump-v2-1-c8a53fd2dd66@codeconstruct.com.au
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

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net: mctp: Set SOCK_RCU_FREE

Bind lookup runs under RCU, so ensure that a socket doesn't go away in
the middle of a lookup.

Fixes: 833ef3b91de6 ("mctp: Populate socket implementation")
Signed-off-b

net: mctp: Set SOCK_RCU_FREE

Bind lookup runs under RCU, so ensure that a socket doesn't go away in
the middle of a lookup.

Fixes: 833ef3b91de6 ("mctp: Populate socket implementation")
Signed-off-by: Matt Johnston <matt@codeconstruct.com.au>
Link: https://patch.msgid.link/20250410-mctp-rcu-sock-v1-1-872de9fdc877@codeconstruct.com.au
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

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treewide: Switch/rename to timer_delete[_sync]()

timer_delete[_sync]() replaces del_timer[_sync](). Convert the whole tree
over and remove the historical wrapper inlines.

Conversion was done with c

treewide: Switch/rename to timer_delete[_sync]()

timer_delete[_sync]() replaces del_timer[_sync](). Convert the whole tree
over and remove the historical wrapper inlines.

Conversion was done with coccinelle plus manual fixups where necessary.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>

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