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

Ensure that the pointer is non-NULL before dereferencing it for debugging
purposes.

Reported-by: Dan Carpenter <redacted>
Signed-off-by: Alex Gartrell <redacted>
---
 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;
 	}
 

-- 
Alex Gartrell <agartrell@fb.com>

	Hello,

On Sun, 5 Oct 2014, Alex Gartrell wrote:

	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 [off-list ref]

Hey Julian,

On 10/05/2014 11:49 PM, Julian Anastasov wrote:

	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.

I've sent an updated patch that does this but I have some questions 
about other stuff that I find mildly confusing.  Specifically I didn't 
realize until looking at the call sites that !dest || daddr = 
dest->addr.ip (but maybe I'm wrong?)

If that's the case, why do we have the following line in __ip_vs_get_out_rt?

                 daddr = dest->addr.ip;

If that's /always/ true then we should add the following line or a 
comment to the same effect to clarify

	BUG_ON(dest && dest->addr.ip != daddr);

If that's not intended to always be true, then should the patch be the 
following?

	...%pI4", dest ? &dest->addr.ip : &daddr);

Thanks,
-- 
Alex Gartrell [off-list ref]

	Hello,

On Mon, 6 Oct 2014, Alex Gartrell wrote:

Hey Julian,

I've sent an updated patch that does this but I have some questions about
other stuff that I find mildly confusing.  Specifically I didn't realize until
looking at the call sites that !dest || daddr = dest->addr.ip (but maybe I'm
wrong?)

If that's the case, why do we have the following line in __ip_vs_get_out_rt?

                daddr = dest->addr.ip;

	Extra line that is not needed...

If that's /always/ true then we should add the following line or a comment to
the same effect to clarify

	BUG_ON(dest && dest->addr.ip != daddr);

	IMHO, BUG_ON is not needed.

If that's not intended to always be true, then should the patch be the
following?

	...%pI4", dest ? &dest->addr.ip : &daddr);

	Using daddr is fine.

Regards

--
Julian Anastasov [off-list ref]