[PATCH net] ipv6: Take rcu_read_lock in __inet6_bind for mapped addresses

[David Ahern]

From: David Ahern <dsah...@gmail.com>

I realized the last patch calls dev_get_by_index_rcu in a branch not
holding the rcu lock. Add the calls to rcu_read_lock and rcu_read_unlock.

Fixes: ec90ad334986 ("ipv6: Consider sk_bound_dev_if when binding a socket to a 
v4 mapped address")
Signed-off-by: David Ahern <dsah...@gmail.com>
---
 net/ipv6/af_inet6.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/net/ipv6/af_inet6.c b/net/ipv6/af_inet6.c
index 93288b9f1697..d99753b5e39b 100644
--- a/net/ipv6/af_inet6.c
+++ b/net/ipv6/af_inet6.c
@@ -321,17 +321,20 @@ static int __inet6_bind(struct sock *sk, struct sockaddr 
*uaddr, int addr_len,
                        goto out;
                }
 
+               rcu_read_lock();
                if (sk->sk_bound_dev_if) {
                        dev = dev_get_by_index_rcu(net, sk->sk_bound_dev_if);
                        if (!dev) {
                                err = -ENODEV;
-                               goto out;
+                               goto out_unlock;
                        }
                }
 
                /* Reproduce AF_INET checks to make the bindings consistent */
                v4addr = addr->sin6_addr.s6_addr32[3];
                chk_addr_ret = inet_addr_type_dev_table(net, dev, v4addr);
+               rcu_read_unlock();
+
                if (!inet_can_nonlocal_bind(net, inet) &&
                    v4addr != htonl(INADDR_ANY) &&
                    chk_addr_ret != RTN_LOCAL &&
-- 
2.11.0