ipv6: Do not leak throw route references

commit 07f615574f8ac499875b21c1142f26308234a92c upstream.

While commit 73ba57bfae4a ("ipv6: fix backtracking for throw routes")
does good job on error propagation to the fib_rules_lookup()
in fib rules core framework that also corrects throw routes
handling, it does not solve route reference leakage problem
happened when we return -EAGAIN to the fib_rules_lookup()
and leave routing table entry referenced in arg->result.

If rule with matched throw route isn't last matched in the
list we overwrite arg->result losing reference on throw
route stored previously forever.

We also partially revert commit ab997ad40839 ("ipv6: fix the
incorrect return value of throw route") since we never return
routing table entry with dst.error == -EAGAIN when
CONFIG_IPV6_MULTIPLE_TABLES is on. Also there is no point
to check for RTF_REJECT flag since it is always set throw
route.

Fixes: 73ba57bfae4a ("ipv6: fix backtracking for throw routes")
Signed-off-by: Serhey Popovych <serhe.popovych@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
[bwh: Backported to 3.16: commit ab997ad40839 was never applied here and does
 not need to be reverted]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/net/ipv6/fib6_rules.c b/net/ipv6/fib6_rules.c
index 27ca79682efbf681a0ab6073f50f8fa73214028e..826a356cc0221db57b6c3937eec2d260c50cad3e 100644 (file)
--- a/net/ipv6/fib6_rules.c
+++ b/net/ipv6/fib6_rules.c
@@ -105,7 +105,8 @@ static int fib6_rule_action(struct fib_rule *rule, struct flowi *flp,
                        flp6->saddr = saddr;
                }
                err = rt->dst.error;
-               goto out;
+               if (err != -EAGAIN)
+                       goto out;
        }
 again:
        ip6_rt_put(rt);