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Re: [PATCH 1/1] IPVS netns exit causes crash in conntrack

To: Hans Schillstrom <hans.schillstrom@xxxxxxxxxxxx>
Subject: Re: [PATCH 1/1] IPVS netns exit causes crash in conntrack
Cc: ja@xxxxxx, wensong@xxxxxxxxxxxx, lvs-devel@xxxxxxxxxxxxxxx, netdev@xxxxxxxxxxxxxxx, netfilter-devel@xxxxxxxxxxxxxxx, kaber@xxxxxxxxx, hans@xxxxxxxxxxxxxxx
From: Simon Horman <horms@xxxxxxxxxxxx>
Date: Mon, 13 Jun 2011 17:08:57 +0900
On Mon, Jun 13, 2011 at 09:06:57AM +0200, Hans Schillstrom wrote:
> Quote from Patric Mc Hardy
> "This looks like nfnetlink.c excited and destroyed the nfnl socket, but
> ip_vs was still holding a reference to a conntrack. When the conntrack
> got destroyed it created a ctnetlink event, causing an oops in
> netlink_has_listeners when trying to use the destroyed nfnetlink
> socket."
> 
> If nf_conntrack_netlink is loaded before ip_vs this is not a problem.
> 
> This patch simply avoids calling ip_vs_conn_drop_conntrack()
> when netns is dying as suggested by Julian.
> 
> Signed-off-by: Hans Schillstrom <hans.schillstrom@xxxxxxxxxxxx>
> ---
>  net/netfilter/ipvs/ip_vs_conn.c |   10 +++++++++-
>  net/netfilter/ipvs/ip_vs_core.c |    1 +
>  2 files changed, 10 insertions(+), 1 deletions(-)
> 
> diff --git a/net/netfilter/ipvs/ip_vs_conn.c b/net/netfilter/ipvs/ip_vs_conn.c
> index bf28ac2..d7dfccb 100644
> --- a/net/netfilter/ipvs/ip_vs_conn.c
> +++ b/net/netfilter/ipvs/ip_vs_conn.c
> @@ -776,8 +776,16 @@ static void ip_vs_conn_expire(unsigned long data)
>               if (cp->control)
>                       ip_vs_control_del(cp);
>  
> -             if (cp->flags & IP_VS_CONN_F_NFCT)
> +             if (cp->flags & IP_VS_CONN_F_NFCT) {
>                       ip_vs_conn_drop_conntrack(cp);
> +             /* Do not access conntracks during subsys cleanup because
> +              * nf_conntrack_find_get can not be used after conntrack
> +              * cleanup for the net.
> +              */

Very minor nit, the comment above should be
intended by one more tab.

> +                     smp_rmb();
> +                     if (ipvs->enable)
> +                             ip_vs_conn_drop_conntrack(cp);
> +             }
>  
>               ip_vs_pe_put(cp->pe);
>               kfree(cp->pe_data);
> diff --git a/net/netfilter/ipvs/ip_vs_core.c b/net/netfilter/ipvs/ip_vs_core.c
> index bfa808f..6f8c934 100644
> --- a/net/netfilter/ipvs/ip_vs_core.c
> +++ b/net/netfilter/ipvs/ip_vs_core.c
> @@ -1945,6 +1945,7 @@ static void __net_exit __ip_vs_dev_cleanup(struct net 
> *net)
>  {
>       EnterFunction(2);
>       net_ipvs(net)->enable = 0;      /* Disable packet reception */
> +     smp_wmb();
>       __ip_vs_sync_cleanup(net);
>       LeaveFunction(2);
>  }
> -- 
> 1.6.0.2
> 
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