When IPv6 host routes with metrics attached are being added, we fetch
the metrics store from the dst via COW through dst_metrics_write_ptr(),
added through commit e5fd387ad5b3.
One remaining problem here is that we actually call into inet_getpeer()
and may end up allocating/creating a new peer from the kmemcache, which
may fail.
Example trace from perf probe (inet_getpeer:41) where create is 1:
ip 6877 [002] 4221.391591: probe:inet_getpeer: (ffffffff8165e293)
85e294 inet_getpeer.part.7 (<- kmem_cache_alloc())
85e578 inet_getpeer
8eb333 ipv6_cow_metrics
8f10ff fib6_commit_metrics
Therefore, a check for NULL on the return of dst_metrics_write_ptr()
is necessary here.
Joint work with Florian Westphal.
Fixes: e5fd387ad5b3 ("ipv6: do not overwrite inetpeer metrics prematurely")
Cc: Michal Kubeček <mkubecek@suse.cz>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
0409c9a5a7