net: ep93xx: 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/ep93xx_eth.c b/drivers/net/ep93xx_eth.c
index 0218349b04500adda12aecbd6aeb3ee2176192a3..9f8df7de060970e0bdba5d87f6a0688b197b37f0 100644 (file)
--- a/drivers/net/ep93xx_eth.c
+++ b/drivers/net/ep93xx_eth.c
@@ -427,7 +427,7 @@ int ep93xx_miiphy_initialize(struct bd_info * const bd)
        struct mii_dev *mdiodev = mdio_alloc();
        if (!mdiodev)
                return -ENOMEM;
-       strncpy(mdiodev->name, "ep93xx_eth0", MDIO_NAME_LEN);
+       strlcpy(mdiodev->name, "ep93xx_eth0", MDIO_NAME_LEN);
        mdiodev->read = ep93xx_miiphy_read;
        mdiodev->write = ep93xx_miiphy_write;