net: armada100_fec: ensure mdiodev->name is NULL terminated after MDIO_NAME_LEN trunc...

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/armada100_fec.c b/drivers/net/armada100_fec.c
index 018891e173c37e1d6ba2e16df11004ce36810185..5d4b90c6ba72ad5f7375d7448053dd539bd64f03 100644 (file)
--- a/drivers/net/armada100_fec.c
+++ b/drivers/net/armada100_fec.c
@@ -717,7 +717,7 @@ int armada100_fec_register(unsigned long base_addr)
        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 = smi_reg_read;
        mdiodev->write = smi_reg_write;