3.6.11.2 stable review patch. If anyone has any objections, please let me know. ------------------ From: Eric Dumazet [ Upstream commit 0d4f0608619de59fd8169dd8e72aadc28d80e715 ] When an ICMP ICMP_FRAG_NEEDED (or ICMPV6_PKT_TOOBIG) message finds a LISTEN socket, and this socket is currently owned by the user, we set TCP_MTU_REDUCED_DEFERRED flag in listener tsq_flags. This is bad because if we clone the parent before it had a chance to clear the flag, the child inherits the tsq_flags value, and next tcp_release_cb() on the child will decrement sk_refcnt. Result is that we might free a live TCP socket, as reported by Dormando. IPv4: Attempt to release TCP socket in state 1 Fix this issue by testing sk_state against TCP_LISTEN early, so that we set TCP_MTU_REDUCED_DEFERRED on appropriate sockets (not a LISTEN one) This bug was introduced in commit 563d34d05786 (tcp: dont drop MTU reduction indications) Reported-by: dormando Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller Signed-off-by: Steven Rostedt --- net/ipv4/tcp_ipv4.c | 14 +++++++------- net/ipv6/tcp_ipv6.c | 7 +++++++ 2 files changed, 14 insertions(+), 7 deletions(-) diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c index c883f4f..e6ed4ae 100644 --- a/net/ipv4/tcp_ipv4.c +++ b/net/ipv4/tcp_ipv4.c @@ -285,13 +285,6 @@ static void tcp_v4_mtu_reduced(struct sock *sk) struct inet_sock *inet = inet_sk(sk); u32 mtu = tcp_sk(sk)->mtu_info; - /* We are not interested in TCP_LISTEN and open_requests (SYN-ACKs - * send out by Linux are always <576bytes so they should go through - * unfragmented). - */ - if (sk->sk_state == TCP_LISTEN) - return; - dst = inet_csk_update_pmtu(sk, mtu); if (!dst) return; @@ -415,6 +408,13 @@ void tcp_v4_err(struct sk_buff *icmp_skb, u32 info) goto out; if (code == ICMP_FRAG_NEEDED) { /* PMTU discovery (RFC1191) */ + /* We are not interested in TCP_LISTEN and open_requests + * (SYN-ACKs send out by Linux are always <576bytes so + * they should go through unfragmented). + */ + if (sk->sk_state == TCP_LISTEN) + goto out; + tp->mtu_info = info; if (!sock_owned_by_user(sk)) { tcp_v4_mtu_reduced(sk); diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c index 8b45fb4..fe48fc9 100644 --- a/net/ipv6/tcp_ipv6.c +++ b/net/ipv6/tcp_ipv6.c @@ -400,6 +400,13 @@ static void tcp_v6_err(struct sk_buff *skb, struct inet6_skb_parm *opt, } if (type == ICMPV6_PKT_TOOBIG) { + /* We are not interested in TCP_LISTEN and open_requests + * (SYN-ACKs send out by Linux are always <576bytes so + * they should go through unfragmented). + */ + if (sk->sk_state == TCP_LISTEN) + goto out; + tp->mtu_info = ntohl(info); if (!sock_owned_by_user(sk)) tcp_v6_mtu_reduced(sk); -- 1.7.10.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/