CVE-2021-47291

In the Linux kernel, the following vulnerability has been resolved: ipv6:
fix another slab-out-of-bounds in fib6_nh_flush_exceptions While running
the self-tests on a KASAN enabled kernel, I observed a slab-out-of-bounds
splat very similar to the one reported in commit 821bbf79fe46 (“ipv6: Fix
KASAN: slab-out-of-bounds Read in fib6_nh_flush_exceptions”). We
additionally need to take care of fib6_metrics initialization failure when
the caller provides an nh. The fix is similar, explicitly free the route
instead of calling fib6_info_release on a half-initialized object.