[PATCH 4.9 024/172] ipv6: Do not leak throw route references

Greg Kroah-Hartman
2017-07-03T13:41:20Z

From: Serhey Popovych <serhe.popovych@gmail.com>

[ Upstream commit 07f615574f8ac499875b21c1142f26308234a92c ]

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
net/ipv6/fib6_rules.c | 22 ++++++----------------
net/ipv6/ip6_fib.c | 3 +--
2 files changed, 7 insertions(+), 18 deletions(-)

--- a/net/ipv6/fib6_rules.c
+++ b/net/ipv6/fib6_rules.c
@@ -32,7 +32,6 @@ struct fib6_rule {
struct dst_entry *fib6_rule_lookup(struct net *net, struct flowi6 *fl6,
int flags, pol_lookup_t lookup)
{
- struct rt6_info *rt;
struct fib_lookup_arg arg = {
.lookup_ptr = lookup,
.flags = FIB_LOOKUP_NOREF,
@@ -44,21 +43,11 @@ struct dst_entry *fib6_rule_lookup(struc
fib_rules_lookup(net->ipv6.fib6_rules_ops,
flowi6_to_flowi(fl6), flags, &arg);

- rt = arg.result;
+ if (arg.result)
+ return arg.result;

- if (!rt) {
- dst_hold(&net->ipv6.ip6_null_entry->dst);
- return &net->ipv6.ip6_null_entry->dst;
- }
-
- if (rt->rt6i_flags & RTF_REJECT &&
- rt->dst.error == -EAGAIN) {
- ip6_rt_put(rt);
- rt = net->ipv6.ip6_null_entry;
- dst_hold(&rt->dst);
- }
-
- return &rt->dst;
+ dst_hold(&net->ipv6.ip6_null_entry->dst);
+ return &net->ipv6.ip6_null_entry->dst;
}

static int fib6_rule_action(struct fib_rule *rule, struct flowi *flp,
@@ -121,7 +110,8 @@ static int fib6_rule_action(struct fib_r
flp6->saddr = saddr;
}
err = rt->dst.error;
- goto out;
+ if (err != -EAGAIN)
+ goto out;
}
again:
ip6_rt_put(rt);
--- a/net/ipv6/ip6_fib.c
+++ b/net/ipv6/ip6_fib.c
@@ -289,8 +289,7 @@ struct dst_entry *fib6_rule_lookup(struc
struct rt6_info *rt;

rt = lookup(net, net->ipv6.fib6_main_tbl, fl6, flags);
- if (rt->rt6i_flags & RTF_REJECT &&
- rt->dst.error == -EAGAIN) {
+ if (rt->dst.error == -EAGAIN) {
ip6_rt_put(rt);
rt = net->ipv6.ip6_null_entry;
dst_hold(&rt->dst);