releases/4.10.5/tcp-fix-various-issues-for-sockets-morphing-to-listen-state.patch

   1 From foo@baz Sat Mar 18 22:03:53 CST 2017
   2 From: Eric Dumazet <edumazet@google.com>
   3 Date: Fri, 3 Mar 2017 14:08:21 -0800
   4 Subject: tcp: fix various issues for sockets morphing to listen state
   5
   6 From: Eric Dumazet <edumazet@google.com>
   7
   8
   9 [ Upstream commit 02b2faaf0af1d85585f6d6980e286d53612acfc2 ]
  10
  11 Dmitry Vyukov reported a divide by 0 triggered by syzkaller, exploiting
  12 tcp_disconnect() path that was never really considered and/or used
  13 before syzkaller ;)
  14
  15 I was not able to reproduce the bug, but it seems issues here are the
  16 three possible actions that assumed they would never trigger on a
  17 listener.
  18
  19 1) tcp_write_timer_handler
  20 2) tcp_delack_timer_handler
  21 3) MTU reduction
  22
  23 Only IPv6 MTU reduction was properly testing TCP_CLOSE and TCP_LISTEN
  24  states from tcp_v6_mtu_reduced()
  25
  26 Signed-off-by: Eric Dumazet <edumazet@google.com>
  27 Reported-by: Dmitry Vyukov <dvyukov@google.com>
  28 Signed-off-by: David S. Miller <davem@davemloft.net>
  29 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  30 ---
  31  net/ipv4/tcp_ipv4.c  |    7 +++++--
  32  net/ipv4/tcp_timer.c |    6 ++++--
  33  2 files changed, 9 insertions(+), 4 deletions(-)
  34
  35 --- a/net/ipv4/tcp_ipv4.c
  36 +++ b/net/ipv4/tcp_ipv4.c
  37 @@ -269,10 +269,13 @@ EXPORT_SYMBOL(tcp_v4_connect);
  38   */
  39  void tcp_v4_mtu_reduced(struct sock *sk)
  40  {
  41 -       struct dst_entry *dst;
  42         struct inet_sock *inet = inet_sk(sk);
  43 -       u32 mtu = tcp_sk(sk)->mtu_info;
  44 +       struct dst_entry *dst;
  45 +       u32 mtu;
  46
  47 +       if ((1 << sk->sk_state) & (TCPF_LISTEN | TCPF_CLOSE))
  48 +               return;
  49 +       mtu = tcp_sk(sk)->mtu_info;
  50         dst = inet_csk_update_pmtu(sk, mtu);
  51         if (!dst)
  52                 return;
  53 --- a/net/ipv4/tcp_timer.c
  54 +++ b/net/ipv4/tcp_timer.c
  55 @@ -249,7 +249,8 @@ void tcp_delack_timer_handler(struct soc
  56
  57         sk_mem_reclaim_partial(sk);
  58
  59 -       if (sk->sk_state == TCP_CLOSE || !(icsk->icsk_ack.pending & ICSK_ACK_TIMER))
  60 +       if (((1 << sk->sk_state) & (TCPF_CLOSE | TCPF_LISTEN)) ||
  61 +           !(icsk->icsk_ack.pending & ICSK_ACK_TIMER))
  62                 goto out;
  63
  64         if (time_after(icsk->icsk_ack.timeout, jiffies)) {
  65 @@ -552,7 +553,8 @@ void tcp_write_timer_handler(struct sock
  66         struct inet_connection_sock *icsk = inet_csk(sk);
  67         int event;
  68
  69 -       if (sk->sk_state == TCP_CLOSE || !icsk->icsk_pending)
  70 +       if (((1 << sk->sk_state) & (TCPF_CLOSE | TCPF_LISTEN)) ||
  71 +           !icsk->icsk_pending)
  72                 goto out;
  73
  74         if (time_after(icsk->icsk_timeout, jiffies)) {