From 0e629694126ca388916f059453a1c36adde219c4 Mon Sep 17 00:00:00 2001 From: Jakub Raczynski Date: Mon, 9 Jun 2025 17:31:46 +0200 Subject: [PATCH] net/mdiobus: Fix potential out-of-bounds read/write access When using publicly available tools like 'mdio-tools' to read/write data from/to network interface and its PHY via mdiobus, there is no verification of parameters passed to the ioctl and it accepts any mdio address. Currently there is support for 32 addresses in kernel via PHY_MAX_ADDR define, but it is possible to pass higher value than that via ioctl. While read/write operation should generally fail in this case, mdiobus provides stats array, where wrong address may allow out-of-bounds read/write. Fix that by adding address verification before read/write operation. While this excludes this access from any statistics, it improves security of read/write operation. Fixes: 080bb352fad00 ("net: phy: Maintain MDIO device and bus statistics") Signed-off-by: Jakub Raczynski Reported-by: Wenjing Shan Signed-off-by: David S. Miller --- drivers/net/phy/mdio_bus.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/drivers/net/phy/mdio_bus.c b/drivers/net/phy/mdio_bus.c index a6bcb0fee863..60fd0cd7cb9c 100644 --- a/drivers/net/phy/mdio_bus.c +++ b/drivers/net/phy/mdio_bus.c @@ -445,6 +445,9 @@ int __mdiobus_read(struct mii_bus *bus, int addr, u32 regnum) lockdep_assert_held_once(&bus->mdio_lock); + if (addr >= PHY_MAX_ADDR) + return -ENXIO; + if (bus->read) retval = bus->read(bus, addr, regnum); else @@ -474,6 +477,9 @@ int __mdiobus_write(struct mii_bus *bus, int addr, u32 regnum, u16 val) lockdep_assert_held_once(&bus->mdio_lock); + if (addr >= PHY_MAX_ADDR) + return -ENXIO; + if (bus->write) err = bus->write(bus, addr, regnum, val); else -- 2.25.1