[PATCH net 0/2] net: ethtool: netlink: Fix notifications for

Maxime Chevallier
2025-02-27T18:24:59Z

It has been found (thanks to Parthiban) that the PLCA ethtool commands
were failing since 6.12, due to the phy_link_topology work. This was
traced back to the ethnl notifications mechanism, in which calls to
ethnl_req_get_phydev() crashed in the notification path following a
->set request.

The typical callsite for ethnl_req_get_phydev() looks like :

phydev = ethnl_req_get_phydev(req_base, tb[ETHTOOL_A_XXX_HEADER],
info->extack);

as 'tb' is NULL in the notification path for the ->prepare_data ethnl
ops, this causes crashes. The solution for that is to change the
prototype of ethnl_req_get_phydev() to perform checks inside the helper
(patch 1).

While investigating that, I realised that the notification path for PHYs
is not correct anyways. As we don't have a netlink request to parse, we
can't know for sure which PHY the notification event targets in the case
of a notification following a ->set request.

Patch 2 introduces a context structure that is used between ->set
requests and the followup notification, to keep track of the PHY that
the original request targeted for the notification.

Thanks Parthiban for the report (not on netdev@ though).

Maxime

Maxime Chevallier (2):
net: ethtool: netlink: Allow NULL nlattrs when getting a phy_device
net: ethtool: netlink: Pass a context for default ethnl notifications

net/ethtool/cabletest.c | 8 ++++----
net/ethtool/linkstate.c | 2 +-
net/ethtool/netlink.c | 21 +++++++++++++++++----
net/ethtool/netlink.h | 5 +++--
net/ethtool/phy.c | 2 +-
net/ethtool/plca.c | 6 +++---
net/ethtool/pse-pd.c | 4 ++--
net/ethtool/stats.c | 2 +-
net/ethtool/strset.c | 2 +-
9 files changed, 33 insertions(+), 19 deletions(-)

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2.48.1