net: fix sk_forward_alloc corruptions

As David found out, sock_queue_err_skb() should be called with socket
lock hold, or we risk sk_forward_alloc corruption, since we use non
atomic operations to update this field.

This patch adds bh_lock_sock()/bh_unlock_sock() pair to three spots.
(BH already disabled)

1) skb_tstamp_tx() 
2) Before calling ip_icmp_error(), in __udp4_lib_err() 
3) Before calling ipv6_icmp_error(), in __udp6_lib_err()

Reported-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 2 insertions, 0 deletions

diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index b9d0d409516f..acdc9be833cc 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -634,7 +634,9 @@ void __udp4_lib_err(struct sk_buff *skb, u32 info, struct udp_table *udptable)
                 if (!harderr || sk->sk_state != TCP_ESTABLISHED)
                         goto out;
         } else {
+                bh_lock_sock(sk);
                 ip_icmp_error(sk, skb, err, uh->dest, info, (u8 *)(uh+1));
+                bh_unlock_sock(sk);
         }
         sk->sk_err = err;
         sk->sk_error_report(sk);