Subject: Re: [PATCH] xfrm: Refcount destination entry on xfrm_lookup

From: Timo Teräs <[email-masked]>
Date: Wed, 16 Mar 2011 10:03:23 +0200

On 03/16/2011 09:12 AM, Steffen Klassert wrote:
> We return a destination entry without refcount if a socket
> policy is found in xfrm_lookup. This triggers a warning on
> a negative refcount when freeeing this dst entry. So take
> a refcount in this case to fix it.
> 
> This refcount was forgotten when xfrm changed to cache bundles
> instead of policies for outgoing flows.
> 
> Signed-off-by: Steffen Klassert <[email-masked]>

Acked-by: Timo Teräs <[email-masked]>

Ok. This is one of the corner cases I did not test: having socket policy
something else than no action. I just didn't have the application ready
for it. Sorry about the bug. And good catch Steffen.

> ---
>  net/xfrm/xfrm_policy.c |    2 ++
>  1 files changed, 2 insertions(+), 0 deletions(-)
> 
> diff --git a/net/xfrm/xfrm_policy.c b/net/xfrm/xfrm_policy.c
> index 027e3c6..15792d8 100644
> --- a/net/xfrm/xfrm_policy.c
> +++ b/net/xfrm/xfrm_policy.c
> @@ -1804,6 +1804,8 @@ restart:
>  				goto no_transform;
>  			}
>  
> +			dst_hold(&xdst->u.dst);
> +
>  			spin_lock_bh(&xfrm_policy_sk_bundle_lock);
>  			xdst->u.dst.next = xfrm_policy_sk_bundles;
>  			xfrm_policy_sk_bundles = &xdst->u.dst;