releases/4.4.133/dccp-fix-tasklet-usage.patch

   1 From foo@baz Wed May 16 16:57:32 CEST 2018
   2 From: Eric Dumazet <edumazet@google.com>
   3 Date: Thu, 3 May 2018 09:39:20 -0700
   4 Subject: dccp: fix tasklet usage
   5
   6 From: Eric Dumazet <edumazet@google.com>
   7
   8 [ Upstream commit a8d7aa17bbc970971ccdf71988ea19230ab368b1 ]
   9
  10 syzbot reported a crash in tasklet_action_common() caused by dccp.
  11
  12 dccp needs to make sure socket wont disappear before tasklet handler
  13 has completed.
  14
  15 This patch takes a reference on the socket when arming the tasklet,
  16 and moves the sock_put() from dccp_write_xmit_timer() to dccp_write_xmitlet()
  17
  18 kernel BUG at kernel/softirq.c:514!
  19 invalid opcode: 0000 [#1] SMP KASAN
  20 Dumping ftrace buffer:
  21    (ftrace buffer empty)
  22 Modules linked in:
  23 CPU: 1 PID: 17 Comm: ksoftirqd/1 Not tainted 4.17.0-rc3+ #30
  24 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
  25 RIP: 0010:tasklet_action_common.isra.19+0x6db/0x700 kernel/softirq.c:515
  26 RSP: 0018:ffff8801d9b3faf8 EFLAGS: 00010246
  27 dccp_close: ABORT with 65423 bytes unread
  28 RAX: 1ffff1003b367f6b RBX: ffff8801daf1f3f0 RCX: 0000000000000000
  29 RDX: ffff8801cf895498 RSI: 0000000000000004 RDI: 0000000000000000
  30 RBP: ffff8801d9b3fc40 R08: ffffed0039f12a95 R09: ffffed0039f12a94
  31 dccp_close: ABORT with 65423 bytes unread
  32 R10: ffffed0039f12a94 R11: ffff8801cf8954a3 R12: 0000000000000000
  33 R13: ffff8801d9b3fc18 R14: dffffc0000000000 R15: ffff8801cf895490
  34 FS:  0000000000000000(0000) GS:ffff8801daf00000(0000) knlGS:0000000000000000
  35 CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
  36 CR2: 0000001b2bc28000 CR3: 00000001a08a9000 CR4: 00000000001406e0
  37 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
  38 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
  39 Call Trace:
  40  tasklet_action+0x1d/0x20 kernel/softirq.c:533
  41  __do_softirq+0x2e0/0xaf5 kernel/softirq.c:285
  42 dccp_close: ABORT with 65423 bytes unread
  43  run_ksoftirqd+0x86/0x100 kernel/softirq.c:646
  44  smpboot_thread_fn+0x417/0x870 kernel/smpboot.c:164
  45  kthread+0x345/0x410 kernel/kthread.c:238
  46  ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:412
  47 Code: 48 8b 85 e8 fe ff ff 48 8b 95 f0 fe ff ff e9 94 fb ff ff 48 89 95 f0 fe ff ff e8 81 53 6e 00 48 8b 95 f0 fe ff ff e9 62 fb ff ff <0f> 0b 48 89 cf 48 89 8d e8 fe ff ff e8 64 53 6e 00 48 8b 8d e8
  48 RIP: tasklet_action_common.isra.19+0x6db/0x700 kernel/softirq.c:515 RSP: ffff8801d9b3faf8
  49
  50 Fixes: dc841e30eaea ("dccp: Extend CCID packet dequeueing interface")
  51 Signed-off-by: Eric Dumazet <edumazet@google.com>
  52 Reported-by: syzbot <syzkaller@googlegroups.com>
  53 Cc: Gerrit Renker <gerrit@erg.abdn.ac.uk>
  54 Cc: dccp@vger.kernel.org
  55 Signed-off-by: David S. Miller <davem@davemloft.net>
  56 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  57 ---
  58  net/dccp/ccids/ccid2.c |   14 ++++++++++++--
  59  net/dccp/timer.c       |    2 +-
  60  2 files changed, 13 insertions(+), 3 deletions(-)
  61
  62 --- a/net/dccp/ccids/ccid2.c
  63 +++ b/net/dccp/ccids/ccid2.c
  64 @@ -126,6 +126,16 @@ static void ccid2_change_l_seq_window(st
  65                                                   DCCPF_SEQ_WMAX));
  66  }
  67
  68 +static void dccp_tasklet_schedule(struct sock *sk)
  69 +{
  70 +       struct tasklet_struct *t = &dccp_sk(sk)->dccps_xmitlet;
  71 +
  72 +       if (!test_and_set_bit(TASKLET_STATE_SCHED, &t->state)) {
  73 +               sock_hold(sk);
  74 +               __tasklet_schedule(t);
  75 +       }
  76 +}
  77 +
  78  static void ccid2_hc_tx_rto_expire(unsigned long data)
  79  {
  80         struct sock *sk = (struct sock *)data;
  81 @@ -166,7 +176,7 @@ static void ccid2_hc_tx_rto_expire(unsig
  82
  83         /* if we were blocked before, we may now send cwnd=1 packet */
  84         if (sender_was_blocked)
  85 -               tasklet_schedule(&dccp_sk(sk)->dccps_xmitlet);
  86 +               dccp_tasklet_schedule(sk);
  87         /* restart backed-off timer */
  88         sk_reset_timer(sk, &hc->tx_rtotimer, jiffies + hc->tx_rto);
  89  out:
  90 @@ -706,7 +716,7 @@ static void ccid2_hc_tx_packet_recv(stru
  91  done:
  92         /* check if incoming Acks allow pending packets to be sent */
  93         if (sender_was_blocked && !ccid2_cwnd_network_limited(hc))
  94 -               tasklet_schedule(&dccp_sk(sk)->dccps_xmitlet);
  95 +               dccp_tasklet_schedule(sk);
  96         dccp_ackvec_parsed_cleanup(&hc->tx_av_chunks);
  97  }
  98
  99 --- a/net/dccp/timer.c
 100 +++ b/net/dccp/timer.c
 101 @@ -230,12 +230,12 @@ static void dccp_write_xmitlet(unsigned
 102         else
 103                 dccp_write_xmit(sk);
 104         bh_unlock_sock(sk);
 105 +       sock_put(sk);
 106  }
 107
 108  static void dccp_write_xmit_timer(unsigned long data)
 109  {
 110         dccp_write_xmitlet(data);
 111 -       sock_put((struct sock *)data);
 112  }
 113
 114  void dccp_init_xmit_timers(struct sock *sk)