netdev - Re: [PATCH net-next] ipv6: Always allocate pcpu memory in a fib6

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Message-Id: <20190604.145522.1019698960837846036.davem@davemloft.net>
Date:   Tue, 04 Jun 2019 14:55:22 -0700 (PDT)
From:   David Miller <davem@...emloft.net>
To:     dsahern@...nel.org
Cc:     netdev@...r.kernel.org, dsahern@...il.com
Subject: Re: [PATCH net-next] ipv6: Always allocate pcpu memory in a fib6_nh

From: David Ahern <dsahern@...nel.org>
Date: Mon,  3 Jun 2019 18:37:03 -0700

> From: David Ahern <dsahern@...il.com>
> 
> A recent commit had an unintended side effect with reject routes:
> rt6i_pcpu is expected to always be initialized for all fib6_info except
> the null entry. The commit mentioned below skips it for reject routes
> and ends up leaking references to the loopback device. For example,
> 
>     ip netns add foo
>     ip -netns foo li set lo up
>     ip -netns foo -6 ro add blackhole 2001:db8:1::1
>     ip netns exec foo ping6 2001:db8:1::1
>     ip netns del foo
> 
> ends up spewing:
>     unregister_netdevice: waiting for lo to become free. Usage count = 3
> 
> The fib_nh_common_init is not needed for reject routes (no ipv4 caching
> or encaps), so move the alloc_percpu_gfp after it and adjust the goto label.
> 
> Fixes: f40b6ae2b612 ("ipv6: Move pcpu cached routes to fib6_nh")
> Signed-off-by: David Ahern <dsahern@...il.com>

Applied.