Merge branch 'ipv6-fix-issues-on-accessing-fib6_metrics'

Wei Wang says:

====================
ipv6: fix issues on accessing fib6_metrics

The latest fix on the memory leak of fib6_metrics still causes
use-after-free.
This patch series first revert the previous fix and propose a new fix
that is more inline with ipv4 logic and is tested to fix the
use-after-free issue reported.
====================

Signed-off-by: David S. Miller <[email protected]>