From: Daniel Golle Date: Tue, 28 Jul 2026 04:52:14 +0000 (+0100) Subject: net: dsa: mt7530: check bus->read() errors in the MDIO regmap backend X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=b4ce102b2cd88424c5860fbbb20b9eb343a93bf4;p=thirdparty%2Fkernel%2Fstable.git net: dsa: mt7530: check bus->read() errors in the MDIO regmap backend bus->read() returns a negative errno on failure, but mt7530_regmap_read() assigns it to a u16, truncating e.g. -ETIMEDOUT into 0xff92, and returns success. The garbage word is then consumed as register data, and read-modify-write cycles write it back to the switch. Check both reads and propagate their errors. The same defect existed in mt7530_mii_read() since the driver was introduced and moved into the regmap backend unchanged. Fixes: b8f126a8d543 ("net-next: dsa: add dsa support for Mediatek MT7530 switch") Signed-off-by: Daniel Golle Reviewed-by: Andrew Lunn Link: https://patch.msgid.link/3c628e48276c2e5522c8795a6be60d11c7a76a7d.1785213071.git.daniel@makrotopia.org Signed-off-by: Jakub Kicinski --- diff --git a/drivers/net/dsa/mt7530-mdio.c b/drivers/net/dsa/mt7530-mdio.c index 11ea924a9f357..784dd58a71589 100644 --- a/drivers/net/dsa/mt7530-mdio.c +++ b/drivers/net/dsa/mt7530-mdio.c @@ -55,8 +55,15 @@ mt7530_regmap_read(void *context, unsigned int reg, unsigned int *val) if (ret < 0) return ret; - lo = bus->read(bus, priv->mdiodev->addr, r); - hi = bus->read(bus, priv->mdiodev->addr, 0x10); + ret = bus->read(bus, priv->mdiodev->addr, r); + if (ret < 0) + return ret; + lo = ret; + + ret = bus->read(bus, priv->mdiodev->addr, 0x10); + if (ret < 0) + return ret; + hi = ret; *val = (hi << 16) | (lo & 0xffff);