netdev - [PATCH][net-next] ipv6: sanitize RCU usage on fib6

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Message-Id: <1550828682-10608-1-git-send-email-lirongqing@baidu.com>
Date:   Fri, 22 Feb 2019 17:44:42 +0800
From:   Li RongQing <lirongqing@...du.com>
To:     netdev@...r.kernel.org
Subject: [PATCH][net-next] ipv6: sanitize RCU usage on fib6_next

using rcu_assign_pointer when setting, which has a memory
barrier to ensure the initialization is seen first.

using rcu_dereference when dereference this pointer

Signed-off-by: Zhang Yu <zhangyu31@...du.com>
Signed-off-by: Li RongQing <lirongqing@...du.com>
---
 net/ipv6/ip6_fib.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/net/ipv6/ip6_fib.c b/net/ipv6/ip6_fib.c
index 6613d8dbb0e5..b73d40d68178 100644
--- a/net/ipv6/ip6_fib.c
+++ b/net/ipv6/ip6_fib.c
@@ -1143,7 +1143,7 @@ static int fib6_add_rt2node(struct fib6_node *fn, struct fib6_info *rt,
 
 		atomic_inc(&rt->fib6_ref);
 		rcu_assign_pointer(rt->fib6_node, fn);
-		rt->fib6_next = iter->fib6_next;
+		rcu_assign_pointer(rt->fib6_next, iter->fib6_next);
 		rcu_assign_pointer(*ins, rt);
 		if (!info->skip_notify)
 			inet6_rt_notify(RTM_NEWROUTE, rt, info, NLM_F_REPLACE);
@@ -1761,7 +1761,9 @@ static void fib6_del_route(struct fib6_table *table, struct fib6_node *fn,
 	RT6_TRACE("fib6_del_route\n");
 
 	/* Unlink it */
-	*rtp = rt->fib6_next;
+	*rtp = rcu_dereference_protected(rt->fib6_next,
+				    lockdep_is_held(&rt->fib6_table->tb6_lock));
+
 	rt->fib6_node = NULL;
 	net->ipv6.rt6_stats->fib_rt_entries--;
 	net->ipv6.rt6_stats->fib_discarded_routes++;
-- 
2.16.2