Nicolas Dichtel <nicolas.dich...@6wind.com> wrote:
> Le 11/08/2016 à 15:17, Florian Westphal a écrit :
> > Don't acquire the readlock anymore and rely on rcu alone.
> >
> > In case writer on other CPU changed policy at the wrong moment (after we
> > obtained sk policy pointer but before we could obtain the reference)
> > just repeat the lookup.
> >
> > Signed-off-by: Florian Westphal <f...@strlen.de>
> Since this patch, our IKEv1 Transport tests (using charon) fail to establish
> the
> connection. If I revert it, the IKE negociation is ok again.
> charon logs are enclosed.
>
> I didn't had time to investigate now, but any idea is welcomed ;-)
I'm an idiot. Thanks for figuring out the faulty commit!
This should fix it (if we succeed grabbing the refcount, then if (err &&
!xfrm_pol_hold_rcu
evaluates to false and we hit last else branch and set pol to ERR_PTR(0)...
diff --git a/net/xfrm/xfrm_policy.c b/net/xfrm/xfrm_policy.c
index fd6986634e6f..5bf7e1bfeac7 100644
--- a/net/xfrm/xfrm_policy.c
+++ b/net/xfrm/xfrm_policy.c
@@ -1268,12 +1268,14 @@ static struct xfrm_policy *xfrm_sk_policy_lookup(const
struct sock *sk, int dir,
err = security_xfrm_policy_lookup(pol->security,
fl->flowi_secid,
policy_to_flow_dir(dir));
- if (!err && !xfrm_pol_hold_rcu(pol))
- goto again;
- else if (err == -ESRCH)
+ if (!err) {
+ if (!xfrm_pol_hold_rcu(pol))
+ goto again;
+ } else if (err == -ESRCH) {
pol = NULL;
- else
+ } else {
pol = ERR_PTR(err);
+ }
} else
