netdev - [PATCH] Revert "net/ipv6: fix metrics leak"

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Date:   Wed, 01 Aug 2018 21:33:37 -0700 (PDT)
From:   David Miller <davem@...emloft.net>
To:     netdev@...r.kernel.org
Subject: [PATCH] Revert "net/ipv6: fix metrics leak"


This reverts commit df18b50448fab1dff093731dfd0e25e77e1afcd1.

This change causes other problems and use-after-free situations as
found by syzbot.

Signed-off-by: David S. Miller <davem@...emloft.net>
---
 net/ipv6/ip6_fib.c | 18 ++++--------------
 1 file changed, 4 insertions(+), 14 deletions(-)

diff --git a/net/ipv6/ip6_fib.c b/net/ipv6/ip6_fib.c
index 211a2d437b56..d212738e9d10 100644
--- a/net/ipv6/ip6_fib.c
+++ b/net/ipv6/ip6_fib.c
@@ -167,22 +167,11 @@ struct fib6_info *fib6_info_alloc(gfp_t gfp_flags)
 	return f6i;
 }
 
-static void fib6_metrics_release(struct fib6_info *f6i)
-{
-	struct dst_metrics *m;
-
-	if (!f6i)
-		return;
-
-	m = f6i->fib6_metrics;
-	if (m != &dst_default_metrics && refcount_dec_and_test(&m->refcnt))
-		kfree(m);
-}
-
 void fib6_info_destroy_rcu(struct rcu_head *head)
 {
 	struct fib6_info *f6i = container_of(head, struct fib6_info, rcu);
 	struct rt6_exception_bucket *bucket;
+	struct dst_metrics *m;
 
 	WARN_ON(f6i->fib6_node);
 
@@ -212,7 +201,9 @@ void fib6_info_destroy_rcu(struct rcu_head *head)
 	if (f6i->fib6_nh.nh_dev)
 		dev_put(f6i->fib6_nh.nh_dev);
 
-	fib6_metrics_release(f6i);
+	m = f6i->fib6_metrics;
+	if (m != &dst_default_metrics && refcount_dec_and_test(&m->refcnt))
+		kfree(m);
 
 	kfree(f6i);
 }
@@ -896,7 +887,6 @@ static void fib6_drop_pcpu_from(struct fib6_info *f6i,
 
 			from = rcu_dereference_protected(pcpu_rt->from,
 					     lockdep_is_held(&table->tb6_lock));
-			fib6_metrics_release(from);
 			rcu_assign_pointer(pcpu_rt->from, NULL);
 			fib6_info_release(from);
 		}
-- 
2.17.1