ppp: Fix generating ifname when empty IFLA_IFNAME is specified
IFLA_IFNAME is nul-term string which means that IFLA_IFNAME buffer can be larger than length of string which contains. Function __rtnl_newlink() generates new own ifname if either IFLA_IFNAME was not specified at all or userspace passed empty nul-term string. It is expected that if userspace does not specify ifname for new ppp netdev then kernel generates one in format "ppp<id>" where id matches to the ppp unit id which can be later obtained by PPPIOCGUNIT ioctl. And it works in this way if IFLA_IFNAME is not specified at all. But it does not work when IFLA_IFNAME is specified with empty string. So fix this logic also for empty IFLA_IFNAME in ppp_nl_newlink() function and correctly generates ifname based on ppp unit identifier if userspace did not provided preferred ifname. Without this patch when IFLA_IFNAME was specified with empty string then kernel created a new ppp interface in format "ppp<id>" but id did not match ppp unit id returned by PPPIOCGUNIT ioctl. In this case id was some number generated by __rtnl_newlink() function. Signed-off-by:Pali Rohár <pali@kernel.org> Fixes: bb8082f6 ("ppp: build ifname using unit identifier for rtnl based devices") Signed-off-by:
David S. Miller <davem@davemloft.net>
parent
2f5501a8
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