From 83180af0b0ea166adf8249f4513beb7355f9b4c9 Mon Sep 17 00:00:00 2001
From: Eric Dumazet <eric.dumazet@gmail.com>
Date: Thu, 23 Sep 2010 21:46:03 +0000
Subject: [PATCH] net: fix rcu use in ip_route_output_slow
__in_dev_get_rtnl(dev_out) is called while RTNL is not held, thus
triggers a lockdep fault.
At this point, we only perform a raw test of dev_out->ip_ptr being NULL,
we dont need to make sure ip_ptr cant changed right after.
We can use rcu_dereference_raw() for this.
Reported-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
---
net/ipv4/route.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index ae1d4a41f1c64..98beda47bc99f 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -2579,7 +2579,7 @@ static int ip_route_output_slow(struct net *net, struct rtable **rp,
goto out;
/* RACE: Check return value of inet_select_addr instead. */
- if (__in_dev_get_rtnl(dev_out) == NULL) {
+ if (rcu_dereference_raw(dev_out->ip_ptr) == NULL) {
dev_put(dev_out);
goto out; /* Wrong error code */
}
--
2.30.2