Commit 637399bf authored by Maxime Chevallier's avatar Maxime Chevallier Committed by Jakub Kicinski
Browse files

net: ethtool: netlink: Allow NULL nlattrs when getting a phy_device 



ethnl_req_get_phydev() is used to lookup a phy_device, in the case an
ethtool netlink command targets a specific phydev within a netdev's
topology.

It takes as a parameter a const struct nlattr *header that's used for
error handling :

       if (!phydev) {
               NL_SET_ERR_MSG_ATTR(extack, header,
                                   "no phy matching phyindex");
               return ERR_PTR(-ENODEV);
       }

In the notify path after a ->set operation however, there's no request
attributes available.

The typical callsite for the above function looks like:

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

So, when tb is NULL (such as in the ethnl notify path), we have a nice
crash.

It turns out that there's only the PLCA command that is in that case, as
the other phydev-specific commands don't have a notification.

This commit fixes the crash by passing the cmd index and the nlattr
array separately, allowing NULL-checking it directly inside the helper.

Fixes: c15e065b ("net: ethtool: Allow passing a phy index for some commands")
Signed-off-by: default avatarMaxime Chevallier <maxime.chevallier@bootlin.com>
Reviewed-by: default avatarKory Maincent <kory.maincent@bootlin.com>
Reported-by: default avatarParthiban Veerasooran <parthiban.veerasooran@microchip.com>
Link: https://patch.msgid.link/20250301141114.97204-1-maxime.chevallier@bootlin.com


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent 4c2d14c4

net/ethtool/cabletest.c

+4 −4
Original line number Diff line number Diff line
@@ -72,8 +72,8 @@ int ethnl_act_cable_test(struct sk_buff *skb, struct genl_info *info) 
	dev = req_info.dev;



	rtnl_lock();

	phydev = ethnl_req_get_phydev(&req_info,

				      tb[ETHTOOL_A_CABLE_TEST_HEADER],

	phydev = ethnl_req_get_phydev(&req_info, tb,

				      ETHTOOL_A_CABLE_TEST_HEADER,

				      info->extack);

	if (IS_ERR_OR_NULL(phydev)) {

		ret = -EOPNOTSUPP;
@@ -339,8 +339,8 @@ int ethnl_act_cable_test_tdr(struct sk_buff *skb, struct genl_info *info) 
		goto out_dev_put;



	rtnl_lock();

	phydev = ethnl_req_get_phydev(&req_info,

				      tb[ETHTOOL_A_CABLE_TEST_TDR_HEADER],

	phydev = ethnl_req_get_phydev(&req_info, tb,

				      ETHTOOL_A_CABLE_TEST_TDR_HEADER,

				      info->extack);

	if (IS_ERR_OR_NULL(phydev)) {

		ret = -EOPNOTSUPP;

net/ethtool/linkstate.c

+1 −1
Original line number Diff line number Diff line
@@ -103,7 +103,7 @@ static int linkstate_prepare_data(const struct ethnl_req_info *req_base, 
	struct phy_device *phydev;

	int ret;



	phydev = ethnl_req_get_phydev(req_base, tb[ETHTOOL_A_LINKSTATE_HEADER],

	phydev = ethnl_req_get_phydev(req_base, tb, ETHTOOL_A_LINKSTATE_HEADER,

				      info->extack);

	if (IS_ERR(phydev)) {

		ret = PTR_ERR(phydev);

net/ethtool/netlink.c

+3 −3
Original line number Diff line number Diff line
@@ -211,7 +211,7 @@ int ethnl_parse_header_dev_get(struct ethnl_req_info *req_info, 
}



struct phy_device *ethnl_req_get_phydev(const struct ethnl_req_info *req_info,

					const struct nlattr *header,

					struct nlattr **tb, unsigned int header,

					struct netlink_ext_ack *extack)

{

	struct phy_device *phydev;
@@ -225,8 +225,8 @@ struct phy_device *ethnl_req_get_phydev(const struct ethnl_req_info *req_info, 
		return req_info->dev->phydev;



	phydev = phy_link_topo_get_phy(req_info->dev, req_info->phy_index);

	if (!phydev) {

		NL_SET_ERR_MSG_ATTR(extack, header,

	if (!phydev && tb) {

		NL_SET_ERR_MSG_ATTR(extack, tb[header],

				    "no phy matching phyindex");

		return ERR_PTR(-ENODEV);

	}

net/ethtool/netlink.h

+3 −2
Original line number Diff line number Diff line
@@ -275,7 +275,8 @@ static inline void ethnl_parse_header_dev_put(struct ethnl_req_info *req_info) 
 * ethnl_req_get_phydev() - Gets the phy_device targeted by this request,

 *			    if any. Must be called under rntl_lock().

 * @req_info:	The ethnl request to get the phy from.

 * @header:	The netlink header, used for error reporting.

 * @tb:		The netlink attributes array, for error reporting.

 * @header:	The netlink header index, used for error reporting.

 * @extack:	The netlink extended ACK, for error reporting.

 *

 * The caller must hold RTNL, until it's done interacting with the returned
@@ -289,7 +290,7 @@ static inline void ethnl_parse_header_dev_put(struct ethnl_req_info *req_info) 
 *	   is returned.

 */

struct phy_device *ethnl_req_get_phydev(const struct ethnl_req_info *req_info,

					const struct nlattr *header,

					struct nlattr **tb, unsigned int header,

					struct netlink_ext_ack *extack);



/**

net/ethtool/phy.c

+1 −1
Original line number Diff line number Diff line
@@ -125,7 +125,7 @@ static int ethnl_phy_parse_request(struct ethnl_req_info *req_base, 
	struct phy_req_info *req_info = PHY_REQINFO(req_base);

	struct phy_device *phydev;



	phydev = ethnl_req_get_phydev(req_base, tb[ETHTOOL_A_PHY_HEADER],

	phydev = ethnl_req_get_phydev(req_base, tb, ETHTOOL_A_PHY_HEADER,

				      extack);

	if (!phydev)

		return 0;