netdev - Re: [PATCH net] ipv6: fix memory leak with multiple tables during netns destruction

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Date:   Fri, 8 Sep 2017 11:24:35 -0700
From:   Cong Wang <xiyou.wangcong@...il.com>
To:     Sabrina Dubroca <sd@...asysnail.net>
Cc:     Linux Kernel Network Developers <netdev@...r.kernel.org>
Subject: Re: [PATCH net] ipv6: fix memory leak with multiple tables during
 netns destruction

On Fri, Sep 8, 2017 at 1:26 AM, Sabrina Dubroca <sd@...asysnail.net> wrote:
> fib6_net_exit only frees the main and local tables. If another table was
> created with fib6_alloc_table, we leak it when the netns is destroyed.
>
> Fix this in the same way ip_fib_net_exit cleans up tables, by walking
> through the whole hashtable of fib6_table's. We can get rid of the
> special cases for local and main, since they're also part of the
> hashtable.
>
> Reproducer:
>     ip netns add x
>     ip -net x -6 rule add from 6003:1::/64 table 100
>     ip netns del x
>
> Reported-by: Jianlin Shi <jishi@...hat.com>
> Fixes: 58f09b78b730 ("[NETNS][IPV6] ip6_fib - make it per network namespace")
> Signed-off-by: Sabrina Dubroca <sd@...asysnail.net>
> ---
>  net/ipv6/ip6_fib.c | 25 +++++++++++++++++++------
>  1 file changed, 19 insertions(+), 6 deletions(-)
>
> diff --git a/net/ipv6/ip6_fib.c b/net/ipv6/ip6_fib.c
> index a3b5c163325f..8280172c806c 100644
> --- a/net/ipv6/ip6_fib.c
> +++ b/net/ipv6/ip6_fib.c
> @@ -191,6 +191,12 @@ void rt6_free_pcpu(struct rt6_info *non_pcpu_rt)
>  }
>  EXPORT_SYMBOL_GPL(rt6_free_pcpu);
>
> +static void fib6_free_table(struct fib6_table *table)
> +{
> +       inetpeer_invalidate_tree(&table->tb6_peers);
> +       kfree(table);
> +}
> +
>  static void fib6_link_table(struct net *net, struct fib6_table *tb)
>  {
>         unsigned int h;
> @@ -2022,15 +2028,22 @@ static int __net_init fib6_net_init(struct net *net)
>
>  static void fib6_net_exit(struct net *net)
>  {
> +       unsigned int i;
> +
>         rt6_ifdown(net, NULL);
>         del_timer_sync(&net->ipv6.ip6_fib_timer);
>
> -#ifdef CONFIG_IPV6_MULTIPLE_TABLES
> -       inetpeer_invalidate_tree(&net->ipv6.fib6_local_tbl->tb6_peers);
> -       kfree(net->ipv6.fib6_local_tbl);
> -#endif
> -       inetpeer_invalidate_tree(&net->ipv6.fib6_main_tbl->tb6_peers);
> -       kfree(net->ipv6.fib6_main_tbl);
> +       for (i = 0; i < FIB_TABLE_HASHSZ; i++) {
> +               struct hlist_head *head = &net->ipv6.fib_table_hash[i];
> +               struct hlist_node *tmp;
> +               struct fib6_table *tb;
> +
> +               hlist_for_each_entry_safe(tb, tmp, head, tb6_hlist) {
> +                       hlist_del(&tb->tb6_hlist);

hlist_del_rcu() ?


> +                       fib6_free_table(tb);

kfree_rcu() in fib6_free_table()?


> +               }
> +       }
> +
>         kfree(net->ipv6.fib_table_hash);
>         kfree(net->ipv6.rt6_stats);
>         fib6_notifier_exit(net);
> --
> 2.14.1
>