1. 01 Sep, 2021 1 commit
    • Wang ShaoBo's avatar
      Bluetooth: fix use-after-free error in lock_sock_nested() · 1bff51ea
      Wang ShaoBo authored
      use-after-free error in lock_sock_nested is reported:
      
      [  179.140137][ T3731] =====================================================
      [  179.142675][ T3731] BUG: KMSAN: use-after-free in lock_sock_nested+0x280/0x2c0
      [  179.145494][ T3731] CPU: 4 PID: 3731 Comm: kworker/4:2 Not tainted 5.12.0-rc6+ #54
      [  179.148432][ T3731] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1ubuntu1.1 04/01/2014
      [  179.151806][ T3731] Workqueue: events l2cap_chan_timeout
      [  179.152730][ T3731] Call Trace:
      [  179.153301][ T3731]  dump_stack+0x24c/0x2e0
      [  179.154063][ T3731]  kmsan_report+0xfb/0x1e0
      [  179.154855][ T3731]  __msan_warning+0x5c/0xa0
      [  179.155579][ T3731]  lock_sock_nested+0x280/0x2c0
      [  179.156436][ T3731]  ? kmsan_get_metadata+0x116/0x180
      [  179.157257][ T3731]  l2cap_sock_teardown_cb+0xb8/0x890
      [  179.158154][ T3731]  ? __msan_metadata_ptr_for_load_8+0x10/0x20
      [  179.159141][ T3731]  ? kmsan_get_metadata+0x116/0x180
      [  179.159994][ T3731]  ? kmsan_get_shadow_origin_ptr+0x84/0xb0
      [  179.160959][ T3731]  ? l2cap_sock_recv_cb+0x420/0x420
      [  179.161834][ T3731]  l2cap_chan_del+0x3e1/0x1d50
      [  179.162608][ T3731]  ? kmsan_get_metadata+0x116/0x180
      [  179.163435][ T3731]  ? kmsan_get_shadow_origin_ptr+0x84/0xb0
      [  179.164406][ T3731]  l2cap_chan_close+0xeea/0x1050
      [  179.165189][ T3731]  ? kmsan_internal_unpoison_shadow+0x42/0x70
      [  179.166180][ T3731]  l2cap_chan_timeout+0x1da/0x590
      [  179.167066][ T3731]  ? __msan_metadata_ptr_for_load_8+0x10/0x20
      [  179.168023][ T3731]  ? l2cap_chan_create+0x560/0x560
      [  179.168818][ T3731]  process_one_work+0x121d/0x1ff0
      [  179.169598][ T3731]  worker_thread+0x121b/0x2370
      [  179.170346][ T3731]  kthread+0x4ef/0x610
      [  179.171010][ T3731]  ? process_one_work+0x1ff0/0x1ff0
      [  179.171828][ T3731]  ? kthread_blkcg+0x110/0x110
      [  179.172587][ T3731]  ret_from_fork+0x1f/0x30
      [  179.173348][ T3731]
      [  179.173752][ T3731] Uninit was created at:
      [  179.174409][ T3731]  kmsan_internal_poison_shadow+0x5c/0xf0
      [  179.175373][ T3731]  kmsan_slab_free+0x76/0xc0
      [  179.176060][ T3731]  kfree+0x3a5/0x1180
      [  179.176664][ T3731]  __sk_destruct+0x8af/0xb80
      [  179.177375][ T3731]  __sk_free+0x812/0x8c0
      [  179.178032][ T3731]  sk_free+0x97/0x130
      [  179.178686][ T3731]  l2cap_sock_release+0x3d5/0x4d0
      [  179.179457][ T3731]  sock_close+0x150/0x450
      [  179.180117][ T3731]  __fput+0x6bd/0xf00
      [  179.180787][ T3731]  ____fput+0x37/0x40
      [  179.181481][ T3731]  task_work_run+0x140/0x280
      [  179.182219][ T3731]  do_exit+0xe51/0x3e60
      [  179.182930][ T3731]  do_group_exit+0x20e/0x450
      [  179.183656][ T3731]  get_signal+0x2dfb/0x38f0
      [  179.184344][ T3731]  arch_do_signal_or_restart+0xaa/0xe10
      [  179.185266][ T3731]  exit_to_user_mode_prepare+0x2d2/0x560
      [  179.186136][ T3731]  syscall_exit_to_user_mode+0x35/0x60
      [  179.186984][ T3731]  do_syscall_64+0xc5/0x140
      [  179.187681][ T3731]  entry_SYSCALL_64_after_hwframe+0x44/0xae
      [  179.188604][ T3731] =====================================================
      
      In our case, there are two Thread A and B:
      
      Context: Thread A:              Context: Thread B:
      
      l2cap_chan_timeout()            __se_sys_shutdown()
        l2cap_chan_close()              l2cap_sock_shutdown()
          l2cap_chan_del()                l2cap_chan_close()
            l2cap_sock_teardown_cb()        l2cap_sock_teardown_cb()
      
      Once l2cap_sock_teardown_cb() excuted, this sock will be marked as SOCK_ZAPPED,
      and can be treated as killable in l2cap_sock_kill() if sock_orphan() has
      excuted, at this time we close sock through sock_close() which end to call
      l2cap_sock_kill() like Thread C:
      
      Context: Thread C:
      
      sock_close()
        l2cap_sock_release()
          sock_orphan()
          l2cap_sock_kill()  #free sock if refcnt is 1
      
      If C completed, Once A or B reaches l2cap_sock_teardown_cb() again,
      use-after-free happened.
      
      We should set chan->data to NULL if sock is destructed, for telling teardown
      operation is not allowed in l2cap_sock_teardown_cb(), and also we should
      avoid killing an already killed socket in l2cap_sock_close_cb().
      Signed-off-by: default avatarWang ShaoBo <bobo.shaobowang@huawei.com>
      Signed-off-by: default avatarLuiz Augusto von Dentz <luiz.von.dentz@intel.com>
      Signed-off-by: default avatarMarcel Holtmann <marcel@holtmann.org>
      1bff51ea
  2. 31 Aug, 2021 2 commits
  3. 30 Aug, 2021 37 commits