diff options
| author | Wei Wang <weiwan@google.com> | 2017-03-01 13:29:48 -0800 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2017-03-02 14:05:41 -0800 |
| commit | 7db92362d2fee5887f6b0c41653b8c9f8f5d6020 (patch) | |
| tree | 4d1b45575d0b490061671c4dddaa32f795013e59 /net | |
| parent | 94352d45092c23874532221b4d1e4721df9d63df (diff) | |
| download | lwn-7db92362d2fee5887f6b0c41653b8c9f8f5d6020.tar.gz lwn-7db92362d2fee5887f6b0c41653b8c9f8f5d6020.zip | |
tcp: fix potential double free issue for fastopen_req
tp->fastopen_req could potentially be double freed if a malicious
user does the following:
1. Enable TCP_FASTOPEN_CONNECT sockopt and do a connect() on the socket.
2. Call connect() with AF_UNSPEC to disconnect the socket.
3. Make this socket a listening socket by calling listen().
4. Accept incoming connections and generate child sockets. All child
sockets will get a copy of the pointer of fastopen_req.
5. Call close() on all sockets. fastopen_req will get freed multiple
times.
Fixes: 19f6d3f3c842 ("net/tcp-fastopen: Add new API support")
Reported-by: Andrey Konovalov <andreyknvl@google.com>
Signed-off-by: Wei Wang <weiwan@google.com>
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.c | 15 |
1 files changed, 12 insertions, 3 deletions
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c index da385ae997a3..cf4555581282 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -1110,9 +1110,14 @@ static int tcp_sendmsg_fastopen(struct sock *sk, struct msghdr *msg, flags = (msg->msg_flags & MSG_DONTWAIT) ? O_NONBLOCK : 0; err = __inet_stream_connect(sk->sk_socket, msg->msg_name, msg->msg_namelen, flags, 1); - inet->defer_connect = 0; - *copied = tp->fastopen_req->copied; - tcp_free_fastopen_req(tp); + /* fastopen_req could already be freed in __inet_stream_connect + * if the connection times out or gets rst + */ + if (tp->fastopen_req) { + *copied = tp->fastopen_req->copied; + tcp_free_fastopen_req(tp); + inet->defer_connect = 0; + } return err; } @@ -2318,6 +2323,10 @@ int tcp_disconnect(struct sock *sk, int flags) memset(&tp->rx_opt, 0, sizeof(tp->rx_opt)); __sk_dst_reset(sk); + /* Clean up fastopen related fields */ + tcp_free_fastopen_req(tp); + inet->defer_connect = 0; + WARN_ON(inet->inet_num && !icsk->icsk_bind_hash); sk->sk_error_report(sk); |