Commit e3adf69f authored May 09, 2026 by David Carlier Committed by Jakub Kicinski May 12, 2026

net: ethtool: phy: avoid NULL deref when PHY driver is unbound



phydev->drv can become NULL while the phy_device is still attached to
its net_device, namely after the PHY driver is unbound via sysfs:

	echo <mdio_id> > /sys/bus/mdio_bus/drivers/<phy_drv>/unbind

phy_remove() clears phydev->drv but doesn't call phy_detach(), so the
phy_device stays in the link topology xarray and ethnl_req_get_phydev()
still hands it back. ETHTOOL_MSG_PHY_GET then oopses on:

	rep_data->drvname = kstrdup(phydev->drv->name, GFP_KERNEL);

drvname is already treated as optional by phy_reply_size(),
phy_fill_reply() and phy_cleanup_data(), so just skip the allocation
when there is no driver bound.

Fixes: 9dd2ad5e ("net: ethtool: phy: Convert the PHY_GET command to generic phy dump")
Cc: stable@vger.kernel.org # 6.13.x
Signed-off-by: David Carlier <devnexen@gmail.com>
Reviewed-by: Maxime Chevallier <maxime.chevallier@bootlin.com>
Tested-by: Maxime Chevallier <maxime.chevallier@bootlin.com>
Link: https://patch.msgid.link/20260509215046.107157-1-devnexen@gmail.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>

parent 2c308cf3

net/ethtool/phy.c

+6 −4

Original line number	Diff line number	Diff line
		@@ -94,11 +94,13 @@ static int phy_prepare_data(const struct ethnl_req_info *req_info,
		if (!rep_data->name)
		return -ENOMEM;

		if (phydev->drv) {
		rep_data->drvname = kstrdup(phydev->drv->name, GFP_KERNEL);
		if (!rep_data->drvname) {
		ret = -ENOMEM;
		goto err_free_name;
		}
		}

		rep_data->upstream_type = pdn->upstream_type;