diff options
| author | Eric Dumazet <edumazet@google.com> | 2013-03-18 07:01:28 +0000 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2013-03-18 13:31:28 -0400 |
| commit | 0d4f0608619de59fd8169dd8e72aadc28d80e715 (patch) | |
| tree | 22a078ce17e33c82c1809594ce1b761c9e30a3d3 /net | |
| parent | b009aac12cd0fe34293c68af8ac48b85be3bd858 (diff) | |
| download | lwn-0d4f0608619de59fd8169dd8e72aadc28d80e715.tar.gz lwn-0d4f0608619de59fd8169dd8e72aadc28d80e715.zip | |
tcp: dont handle MTU reduction on LISTEN socket
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 <dormando@rydia.net>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net')
| -rw-r--r-- | net/ipv4/tcp_ipv4.c | 14 | ||||
| -rw-r--r-- | 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 4a8ec457310f..d09203c63264 100644 --- a/net/ipv4/tcp_ipv4.c +++ b/net/ipv4/tcp_ipv4.c @@ -274,13 +274,6 @@ 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; @@ -408,6 +401,13 @@ 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 9b6460055df5..f6d629fd6aee 100644 --- a/net/ipv6/tcp_ipv6.c +++ b/net/ipv6/tcp_ipv6.c @@ -389,6 +389,13 @@ 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); |