releases/4.4.177/tcp-dccp-remove-reqsk_put-from-inet_child_forget.patch

   1 From da8ab57863ed7e912d10b179b6bdc652f635bd19 Mon Sep 17 00:00:00 2001
   2 From: Eric Dumazet <edumazet@google.com>
   3 Date: Mon, 11 Sep 2017 15:58:38 -0700
   4 Subject: tcp/dccp: remove reqsk_put() from inet_child_forget()
   5
   6 From: Eric Dumazet <edumazet@google.com>
   7
   8 commit da8ab57863ed7e912d10b179b6bdc652f635bd19 upstream.
   9
  10 Back in linux-4.4, I inadvertently put a call to reqsk_put() in
  11 inet_child_forget(), forgetting it could be called from two different
  12 points.
  13
  14 In the case it is called from inet_csk_reqsk_queue_add(), we want to
  15 keep the reference on the request socket, since it is released later by
  16 the caller (tcp_v{4|6}_rcv())
  17
  18 This bug never showed up because atomic_dec_and_test() was not signaling
  19 the underflow, and SLAB_DESTROY_BY RCU semantic for request sockets
  20 prevented the request to be put in quarantine.
  21
  22 Recent conversion of socket refcount from atomic_t to refcount_t finally
  23 exposed the bug.
  24
  25 So move the reqsk_put() to inet_csk_listen_stop() to fix this.
  26
  27 Thanks to Shankara Pailoor for using syzkaller and providing
  28 a nice set of .config and C repro.
  29
  30 WARNING: CPU: 2 PID: 4277 at lib/refcount.c:186
  31 refcount_sub_and_test+0x167/0x1b0 lib/refcount.c:186
  32 Kernel panic - not syncing: panic_on_warn set ...
  33
  34 CPU: 2 PID: 4277 Comm: syz-executor0 Not tainted 4.13.0-rc7 #3
  35 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
  36 Ubuntu-1.8.2-1ubuntu1 04/01/2014
  37 Call Trace:
  38  <IRQ>
  39  __dump_stack lib/dump_stack.c:16 [inline]
  40  dump_stack+0xf7/0x1aa lib/dump_stack.c:52
  41  panic+0x1ae/0x3a7 kernel/panic.c:180
  42  __warn+0x1c4/0x1d9 kernel/panic.c:541
  43  report_bug+0x211/0x2d0 lib/bug.c:183
  44  fixup_bug+0x40/0x90 arch/x86/kernel/traps.c:190
  45  do_trap_no_signal arch/x86/kernel/traps.c:224 [inline]
  46  do_trap+0x260/0x390 arch/x86/kernel/traps.c:273
  47  do_error_trap+0x118/0x340 arch/x86/kernel/traps.c:310
  48  do_invalid_op+0x1b/0x20 arch/x86/kernel/traps.c:323
  49  invalid_op+0x18/0x20 arch/x86/entry/entry_64.S:846
  50 RIP: 0010:refcount_sub_and_test+0x167/0x1b0 lib/refcount.c:186
  51 RSP: 0018:ffff88006e006b60 EFLAGS: 00010286
  52 RAX: 0000000000000026 RBX: 0000000000000000 RCX: 0000000000000000
  53 RDX: 0000000000000026 RSI: 1ffff1000dc00d2c RDI: ffffed000dc00d60
  54 RBP: ffff88006e006bf0 R08: 0000000000000001 R09: 0000000000000000
  55 R10: 0000000000000000 R11: 0000000000000000 R12: 1ffff1000dc00d6d
  56 R13: 00000000ffffffff R14: 0000000000000001 R15: ffff88006ce9d340
  57  refcount_dec_and_test+0x1a/0x20 lib/refcount.c:211
  58  reqsk_put+0x71/0x2b0 include/net/request_sock.h:123
  59  tcp_v4_rcv+0x259e/0x2e20 net/ipv4/tcp_ipv4.c:1729
  60  ip_local_deliver_finish+0x2e2/0xba0 net/ipv4/ip_input.c:216
  61  NF_HOOK include/linux/netfilter.h:248 [inline]
  62  ip_local_deliver+0x1ce/0x6d0 net/ipv4/ip_input.c:257
  63  dst_input include/net/dst.h:477 [inline]
  64  ip_rcv_finish+0x8db/0x19c0 net/ipv4/ip_input.c:397
  65  NF_HOOK include/linux/netfilter.h:248 [inline]
  66  ip_rcv+0xc3f/0x17d0 net/ipv4/ip_input.c:488
  67  __netif_receive_skb_core+0x1fb7/0x31f0 net/core/dev.c:4298
  68  __netif_receive_skb+0x2c/0x1b0 net/core/dev.c:4336
  69  process_backlog+0x1c5/0x6d0 net/core/dev.c:5102
  70  napi_poll net/core/dev.c:5499 [inline]
  71  net_rx_action+0x6d3/0x14a0 net/core/dev.c:5565
  72  __do_softirq+0x2cb/0xb2d kernel/softirq.c:284
  73  do_softirq_own_stack+0x1c/0x30 arch/x86/entry/entry_64.S:898
  74  </IRQ>
  75  do_softirq.part.16+0x63/0x80 kernel/softirq.c:328
  76  do_softirq kernel/softirq.c:176 [inline]
  77  __local_bh_enable_ip+0x84/0x90 kernel/softirq.c:181
  78  local_bh_enable include/linux/bottom_half.h:31 [inline]
  79  rcu_read_unlock_bh include/linux/rcupdate.h:705 [inline]
  80  ip_finish_output2+0x8ad/0x1360 net/ipv4/ip_output.c:231
  81  ip_finish_output+0x74e/0xb80 net/ipv4/ip_output.c:317
  82  NF_HOOK_COND include/linux/netfilter.h:237 [inline]
  83  ip_output+0x1cc/0x850 net/ipv4/ip_output.c:405
  84  dst_output include/net/dst.h:471 [inline]
  85  ip_local_out+0x95/0x160 net/ipv4/ip_output.c:124
  86  ip_queue_xmit+0x8c6/0x1810 net/ipv4/ip_output.c:504
  87  tcp_transmit_skb+0x1963/0x3320 net/ipv4/tcp_output.c:1123
  88  tcp_send_ack.part.35+0x38c/0x620 net/ipv4/tcp_output.c:3575
  89  tcp_send_ack+0x49/0x60 net/ipv4/tcp_output.c:3545
  90  tcp_rcv_synsent_state_process net/ipv4/tcp_input.c:5795 [inline]
  91  tcp_rcv_state_process+0x4876/0x4b60 net/ipv4/tcp_input.c:5930
  92  tcp_v4_do_rcv+0x58a/0x820 net/ipv4/tcp_ipv4.c:1483
  93  sk_backlog_rcv include/net/sock.h:907 [inline]
  94  __release_sock+0x124/0x360 net/core/sock.c:2223
  95  release_sock+0xa4/0x2a0 net/core/sock.c:2715
  96  inet_wait_for_connect net/ipv4/af_inet.c:557 [inline]
  97  __inet_stream_connect+0x671/0xf00 net/ipv4/af_inet.c:643
  98  inet_stream_connect+0x58/0xa0 net/ipv4/af_inet.c:682
  99  SYSC_connect+0x204/0x470 net/socket.c:1628
 100  SyS_connect+0x24/0x30 net/socket.c:1609
 101  entry_SYSCALL_64_fastpath+0x18/0xad
 102 RIP: 0033:0x451e59
 103 RSP: 002b:00007f474843fc08 EFLAGS: 00000216 ORIG_RAX: 000000000000002a
 104 RAX: ffffffffffffffda RBX: 0000000000718000 RCX: 0000000000451e59
 105 RDX: 0000000000000010 RSI: 0000000020002000 RDI: 0000000000000007
 106 RBP: 0000000000000046 R08: 0000000000000000 R09: 0000000000000000
 107 R10: 0000000000000000 R11: 0000000000000216 R12: 0000000000000000
 108 R13: 00007ffc040a0f8f R14: 00007f47484409c0 R15: 0000000000000000
 109
 110 Fixes: ebb516af60e1 ("tcp/dccp: fix race at listener dismantle phase")
 111 Signed-off-by: Eric Dumazet <edumazet@google.com>
 112 Reported-by: Shankara Pailoor <sp3485@columbia.edu>
 113 Tested-by: Shankara Pailoor <sp3485@columbia.edu>
 114 Signed-off-by: David S. Miller <davem@davemloft.net>
 115 Cc: Guillaume Nault <gnault@redhat.com>
 116 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
 117
 118 ---
 119  net/ipv4/inet_connection_sock.c |    2 +-
 120  1 file changed, 1 insertion(+), 1 deletion(-)
 121
 122 --- a/net/ipv4/inet_connection_sock.c
 123 +++ b/net/ipv4/inet_connection_sock.c
 124 @@ -787,7 +787,6 @@ static void inet_child_forget(struct soc
 125                 tcp_sk(child)->fastopen_rsk = NULL;
 126         }
 127         inet_csk_destroy_sock(child);
 128 -       reqsk_put(req);
 129  }
 130
 131  struct sock *inet_csk_reqsk_queue_add(struct sock *sk,
 132 @@ -858,6 +857,7 @@ void inet_csk_listen_stop(struct sock *s
 133                 sock_hold(child);
 134
 135                 inet_child_forget(sk, req, child);
 136 +               reqsk_put(req);
 137                 bh_unlock_sock(child);
 138                 local_bh_enable();
 139                 sock_put(child);