Re: [PATCH net-next] ipvs: Avoid null-pointer deref in debug code

[Julian Anastasov <ja@xxxxxx>]

        Hello,

On Sun, 5 Oct 2014, Alex Gartrell wrote:

> Ensure that the pointer is non-NULL before dereferencing it for debugging
> purposes.
> 
> Reported-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
> Signed-off-by: Alex Gartrell <agartrell@xxxxxx>
> ---
>  net/netfilter/ipvs/ip_vs_xmit.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/net/netfilter/ipvs/ip_vs_xmit.c b/net/netfilter/ipvs/ip_vs_xmit.c
> index 91f17c1..06bba9b 100644
> --- a/net/netfilter/ipvs/ip_vs_xmit.c
> +++ b/net/netfilter/ipvs/ip_vs_xmit.c
> @@ -316,7 +316,7 @@ __ip_vs_get_out_rt(int skb_af, struct sk_buff *skb, 
> struct ip_vs_dest *dest,
>       if (unlikely(crosses_local_route_boundary(skb_af, skb, rt_mode,
>                                                 local))) {
>               IP_VS_DBG_RL("We are crossing local and non-local addresses"
> -                          " daddr=%pI4\n", &dest->addr.ip);
> +                          " daddr=%pI4\n", dest ? &dest->addr.ip : NULL);
>               goto err_put;
>       }
>  
> @@ -458,7 +458,7 @@ __ip_vs_get_out_rt_v6(int skb_af, struct sk_buff *skb, 
> struct ip_vs_dest *dest,
>       if (unlikely(crosses_local_route_boundary(skb_af, skb, rt_mode,
>                                                 local))) {
>               IP_VS_DBG_RL("We are crossing local and non-local addresses"
> -                          " daddr=%pI6\n", &dest->addr.in6);
> +                          " daddr=%pI6\n", dest ? &dest->addr.in6 : NULL);
>               goto err_put;
>       }

        You have to print the "daddr" variable as
it was done before your patchset in the
"Stopping traffic to %s address, dest: %p..." message
because dest is not present in all cases, for example,
for *bypass_xmit. Other places provide cp->daddr but
for backup server some conns can live without cp->dest.

Regards

--
Julian Anastasov <ja@xxxxxx>
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