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Re: [PATCH net-next] ipvs: fix ipv6 route unreach panic

To: Alex Gartrell <agartrell@xxxxxx>
Subject: Re: [PATCH net-next] ipvs: fix ipv6 route unreach panic
Cc: ja@xxxxxx, lvs-devel@xxxxxxxxxxxxxxx, kernel-team@xxxxxx, Hannes Frederic Sowa <hannes@xxxxxxxxxxxxxxxxxxx>
From: Simon Horman <horms@xxxxxxxxxxxx>
Date: Tue, 14 Jul 2015 17:20:41 +0900
[Cc Hannes]

On Fri, Jun 26, 2015 at 03:18:45AM -0700, Alex Gartrell wrote:
> Previously there was a trivial panic
> 
> unshare -n /bin/bash <<EOF
> ip addr add dev lo face::1/128
> ipvsadm -A -t [face::1]:15213
> ipvsadm -a -t [face::1]:15213 -r b00c::1
> echo boom | nc face::1 15213
> EOF
> 
> This patch allows us to replicate the net logic above and simply capture
> the skb_dst(skb)->dev and use that for the purpose of the invocation.
> 
> Signed-off-by: Alex Gartrell <agartrell@xxxxxx>
> ---
>  net/netfilter/ipvs/ip_vs_xmit.c | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/net/netfilter/ipvs/ip_vs_xmit.c b/net/netfilter/ipvs/ip_vs_xmit.c
> index bf66a86..b99d806 100644
> --- a/net/netfilter/ipvs/ip_vs_xmit.c
> +++ b/net/netfilter/ipvs/ip_vs_xmit.c
> @@ -505,6 +505,13 @@ err_put:
>       return -1;
>  
>  err_unreach:
> +     /* The ip6_link_failure function requires the dev field to be set
> +      * in order to get the net (further for the sake of fwmark
> +      * reflection).
> +      */
> +     if (!skb->dev)
> +             skb->dev = skb_dst(skb)->dev;
> +
>       dst_link_failure(skb);
>       return -1;
>  }


My reading of this is that the above:

Fixes: 1eb4f7582868 ("ipv6: in case of link failure remove route directly 
instead of letting it expire")

As it seems to me that it is that patch that causes ip6_link_failure to
require the dev field to be set.

Does that seem sane?
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