net: dsa: felix: ensure mii_bus->name is NULL terminated after MDIO_NAME_LEN truncation

strncpy() simply bails out when copying a source string whose size
exceeds the destination string size, potentially leaving the destination
string unterminated.

One possible way to address is to pass MDIO_NAME_LEN - 1 and a
previously zero-initialized destination string, but this is more
difficult to maintain.

The chosen alternative is to use strlcpy(), which properly limits the
copy len in the (srclen >= size) case to "size - 1", and which is also
more efficient than the strncpy() byte-by-byte implementation by using
memcpy. The destination string returned by strlcpy() is always NULL
terminated.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Ramon Fried <rfried.dev@gmail.com>

diff --git a/drivers/net/mscc_eswitch/felix_switch.c b/drivers/net/mscc_eswitch/felix_switch.c
index 0cab671..711dd44 100644 (file)
--- a/drivers/net/mscc_eswitch/felix_switch.c
+++ b/drivers/net/mscc_eswitch/felix_switch.c
@@ -257,7 +257,7 @@ static void felix_init(struct udevice *dev)
        priv->imdio.read = felix_mdio_read;
        priv->imdio.write = felix_mdio_write;
        priv->imdio.priv = priv->imdio_base + FELIX_PM_IMDIO_BASE;
-       strncpy(priv->imdio.name, dev->name, MDIO_NAME_LEN);
+       strlcpy(priv->imdio.name, dev->name, MDIO_NAME_LEN);
 
        /* set up CPU port */
        out_le32(base + FELIX_QSYS_SYSTEM_EXT_CPU_CFG,
@@ -302,7 +302,7 @@ static int felix_probe(struct udevice *dev)
                mii_bus->read = felix_mdio_read;
                mii_bus->write = felix_mdio_write;
                mii_bus->priv = priv->imdio_base + FELIX_PM_IMDIO_BASE;
-               strncpy(mii_bus->name, dev->name, MDIO_NAME_LEN);
+               strlcpy(mii_bus->name, dev->name, MDIO_NAME_LEN);
                mdio_register(mii_bus);
        }