ali1234:

In /lib/functions/system.sh is the code:

mac_dirty=$(strings "$part" | sed -n 's/^'"$key"'=//p')

$part is the mtd containing the uboot environment.

When uboot writes its env it only erases sectors it needs to. If you delete a lot of env variables, later sectors can still contain old data. strings will read from those sectors and sed will potentially see multiple copies of the ethaddr variable. It can then output multiple copies of the ethaddr, which causes macaddr_canonicalize to reject the input because it is longer than 17 characters

A simple fix would be to do something like:

mac_dirty=$(strings "$part" | sed -n 's/^'"$key"'=//p' | head -n 1)

There may be a better way with some sed magic.