netdev - [PATCH net-next] net/ipv6: fix LOCKDEP issue in rt6_remove_exception

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Message-Id: <20180424162249.41820-1-edumazet@google.com>
Date:   Tue, 24 Apr 2018 09:22:49 -0700
From:   Eric Dumazet <edumazet@...gle.com>
To:     "David S . Miller" <davem@...emloft.net>
Cc:     netdev <netdev@...r.kernel.org>,
        Eric Dumazet <edumazet@...gle.com>,
        Eric Dumazet <eric.dumazet@...il.com>,
        David Ahern <dsahern@...il.com>
Subject: [PATCH net-next] net/ipv6: fix LOCKDEP issue in rt6_remove_exception_rt()

rt6_remove_exception_rt() is called under rcu_read_lock() only.

We lock rt6_exception_lock a bit later, so we do not hold
rt6_exception_lock yet.

Fixes: 8a14e46f1402 ("net/ipv6: Fix missing rcu dereferences on from")
Signed-off-by: Eric Dumazet <edumazet@...gle.com>
Reported-by: syzbot <syzkaller@...glegroups.com>
Cc: David Ahern <dsahern@...il.com>
---
 net/ipv6/route.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index ac3e51631c659b5c5c8a93c17011cb7f3ad266e2..432c4bcc1111085671f32987e4673e47898085a3 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -1546,8 +1546,7 @@ static int rt6_remove_exception_rt(struct rt6_info *rt)
 	struct fib6_info *from;
 	int err;
 
-	from = rcu_dereference_protected(rt->from,
-					 lockdep_is_held(&rt6_exception_lock));
+	from = rcu_dereference(rt->from);
 	if (!from ||
 	    !(rt->rt6i_flags & RTF_CACHE))
 		return -EINVAL;
-- 
2.17.0.484.g0c8726318c-goog