From: Niklas Söderlund niklas.soderlund+renesas@ragnatech.se
[ Upstream commit 569bf6d481b0b823c3c9c3b8be77908fd7caf66b ]
When reading registers from the PHY using the SIOCGMIIREG IOCTL any errors returned from either mdiobus_read() or mdiobus_c45_read() are ignored, and parts of the returned error is passed as the register value back to user-space.
For example, if mdiobus_c45_read() is used with a bus that do not implement the read_c45() callback -EOPNOTSUPP is returned. This is however directly stored in mii_data->val_out and returned as the registers content. As val_out is a u16 the error code is truncated and returned as a plausible register value.
Fix this by first checking the return value for errors before returning it as the register content.
Before this patch,
# phytool read eth0/0:1/0 0xffa1
After this change,
$ phytool read eth0/0:1/0 error: phy_read (-95)
Signed-off-by: Niklas Söderlund niklas.soderlund+renesas@ragnatech.se Reviewed-by: Florian Fainelli florian.fainelli@broadcom.com Reviewed-by: Andrew Lunn andrew@lunn.ch Reviewed-by: Yoshihiro Shimoda yoshihiro.shimoda.uh@renesas.com Tested-by: Yoshihiro Shimoda yoshihiro.shimoda.uh@renesas.com Reviewed-by: Geert Uytterhoeven geert+renesas@glider.be Link: https://patch.msgid.link/20240903171536.628930-1-niklas.soderlund+renesas@ra... Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/net/phy/phy.c | 17 +++++++++++------ 1 file changed, 11 insertions(+), 6 deletions(-)
diff --git a/drivers/net/phy/phy.c b/drivers/net/phy/phy.c index 785182fa5fe01..b88d857ea23b8 100644 --- a/drivers/net/phy/phy.c +++ b/drivers/net/phy/phy.c @@ -342,14 +342,19 @@ int phy_mii_ioctl(struct phy_device *phydev, struct ifreq *ifr, int cmd) if (mdio_phy_id_is_c45(mii_data->phy_id)) { prtad = mdio_phy_id_prtad(mii_data->phy_id); devad = mdio_phy_id_devad(mii_data->phy_id); - mii_data->val_out = mdiobus_c45_read( - phydev->mdio.bus, prtad, devad, - mii_data->reg_num); + ret = mdiobus_c45_read(phydev->mdio.bus, prtad, devad, + mii_data->reg_num); + } else { - mii_data->val_out = mdiobus_read( - phydev->mdio.bus, mii_data->phy_id, - mii_data->reg_num); + ret = mdiobus_read(phydev->mdio.bus, mii_data->phy_id, + mii_data->reg_num); } + + if (ret < 0) + return ret; + + mii_data->val_out = ret; + return 0;
case SIOCSMIIREG: