ethtool: ignore unused/unreliable fields in set_eee op

This function is used with the set_eee() ethtool operation. Certain
fields of struct ethtool_keee() are relevant only for the get_eee()
operation. In addition, in case of the ioctl interface, we have no
guarantee that userspace sends sane values in struct ethtool_eee.
Therefore explicitly ignore all fields not needed for set_eee().
This protects from drivers trying to use unchecked and unreliable
data, relying on specific userspace behavior.

Note: Such unsafe driver behavior has been found and fixed in the
tg3 driver.

Signed-off-by: Heiner Kallweit <[email protected]>
Reviewed-by: Andrew Lunn <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>

Author: hkallweit

net/ethtool/ioctl.c

@@ -1514,17 +1514,12 @@ static void eee_to_keee(struct ethtool_keee *keee,
 {
 	memset(keee, 0, sizeof(*keee));
 
-	keee->eee_active = eee->eee_active;
 	keee->eee_enabled = eee->eee_enabled;
 	keee->tx_lpi_enabled = eee->tx_lpi_enabled;
 	keee->tx_lpi_timer = eee->tx_lpi_timer;
 
-	ethtool_convert_legacy_u32_to_link_mode(keee->supported,
-						eee->supported);
 	ethtool_convert_legacy_u32_to_link_mode(keee->advertised,
 						eee->advertised);
-	ethtool_convert_legacy_u32_to_link_mode(keee->lp_advertised,
-						eee->lp_advertised);
 }
 
 static void keee_to_eee(struct ethtool_eee *eee,