net: at91_emac: ensure mdiodev->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/at91_emac.c b/drivers/net/at91_emac.c
index e40b94ad892d191f2ffa61bfe57b620b5e49fd4c..b4581d8c932034c3bf4a048b007cd905f2569cfc 100644 (file)
--- a/drivers/net/at91_emac.c
+++ b/drivers/net/at91_emac.c
@@ -507,7 +507,7 @@ int at91emac_register(struct bd_info *bis, unsigned long iobase)
        struct mii_dev *mdiodev = mdio_alloc();
        if (!mdiodev)
                return -ENOMEM;
-       strncpy(mdiodev->name, dev->name, MDIO_NAME_LEN);
+       strlcpy(mdiodev->name, dev->name, MDIO_NAME_LEN);
        mdiodev->read = at91emac_mii_read;
        mdiodev->write = at91emac_mii_write;