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

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Date:	Mon, 13 Jun 2011 17:08:57 +0900
From:	Simon Horman <horms@...ge.net.au>
To:	Hans Schillstrom <hans.schillstrom@...csson.com>
Cc:	ja@....bg, wensong@...ux-vs.org, lvs-devel@...r.kernel.org,
	netdev@...r.kernel.org, netfilter-devel@...r.kernel.org,
	kaber@...sh.net, hans@...illstrom.com
Subject: Re: [PATCH 1/1] IPVS  netns exit causes crash in conntrack

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@...csson.com>
> ---
>  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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