Re: [PATCH] Bluetooth: Prevent double register of suspend

[Luiz Augusto von Dentz <luiz.dentz@gmail.com>]

Hi Abhishek,

On Mon, Sep 26, 2022 at 4:31 PM Abhishek Pandit-Subedi
<abhishekpandit@google.com> wrote:
>
> From: Abhishek Pandit-Subedi <abhishekpandit@chromium.org>
>
> Suspend notifier should only be registered and unregistered once per
> hdev. Since hci_sock and hci_register_dev run in different work queues
> (sock vs driver), add hci_dev_lock to avoid double registering.
>
> Reported-by: syzbot <syzkaller@googlegroups.com>
> Signed-off-by: Abhishek Pandit-Subedi <abhishekpandit@chromium.org>
> ---
> This is fixing a syzbot reported warning. Tested in the following ways:
> * Normal start-up of driver with bluez.
> * Start/stop loop using HCI_USER_CHANNEL (sock path).
> * USB reset triggering hci_dev_unregister (driver path).
>
> ------------[ cut here ]------------
> double register detected
> WARNING: CPU: 0 PID: 2657 at kernel/notifier.c:27
> notifier_chain_register kernel/notifier.c:27 [inline]
> WARNING: CPU: 0 PID: 2657 at kernel/notifier.c:27
> notifier_chain_register+0x5c/0x124 kernel/notifier.c:22
> Modules linked in:
> CPU: 0 PID: 2657 Comm: syz-executor212 Not tainted
> 5.10.136-syzkaller-19376-g6f46a5fe0124 #0
>   8f0771607702f5ef7184d2ee33bd0acd70219fc4
>   Hardware name: Google Google Compute Engine/Google Compute Engine,
>   BIOS Google 07/22/2022
>   RIP: 0010:notifier_chain_register kernel/notifier.c:27 [inline]
>   RIP: 0010:notifier_chain_register+0x5c/0x124 kernel/notifier.c:22
>   Code: 6a 41 00 4c 8b 23 4d 85 e4 0f 84 88 00 00 00 e8 c2 1e 19 00 49
>   39 ec 75 18 e8 b8 1e 19 00 48 c7 c7 80 6d ca 84 e8 2c 68 48 03 <0f> 0b
>      e9 af 00 00 00 e8 a0 1e 19 00 48 8d 7d 10 48 89 f8 48 c1 e8
>      RSP: 0018:ffffc900009d7da8 EFLAGS: 00010286
>      RAX: 0000000000000000 RBX: ffff8881076fd1d8 RCX: 0000000000000000
>      RDX: 0000001810895100 RSI: ffff888110895100 RDI: fffff5200013afa7
>      RBP: ffff88811a4191d0 R08: ffffffff813b8ca1 R09: 0000000080000000
>      R10: 0000000000000000 R11: 0000000000000005 R12: ffff88811a4191d0
>      R13: dffffc0000000000 R14: 0000000000000000 R15: 0000000000000000
>      FS: 00005555571f5300(0000) GS:ffff8881f6c00000(0000)
>      knlGS:0000000000000000
>      CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>      CR2: 000078e3857f3075 CR3: 000000010d668000 CR4: 00000000003506f0
>      DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
>      DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
>      Call Trace:
>      blocking_notifier_chain_register+0x8c/0xa6 kernel/notifier.c:254
>      hci_register_suspend_notifier net/bluetooth/hci_core.c:2733
>      [inline]
>      hci_register_suspend_notifier+0x6b/0x7c
>      net/bluetooth/hci_core.c:2727
>      hci_sock_release+0x270/0x3cf net/bluetooth/hci_sock.c:889
>      __sock_release+0xcd/0x1de net/socket.c:597
>      sock_close+0x18/0x1c net/socket.c:1267
>      __fput+0x418/0x729 fs/file_table.c:281
>      task_work_run+0x12b/0x15b kernel/task_work.c:151
>      tracehook_notify_resume include/linux/tracehook.h:188 [inline]
>      exit_to_user_mode_loop kernel/entry/common.c:165 [inline]
>      exit_to_user_mode_prepare+0x8f/0x130 kernel/entry/common.c:192
>      syscall_exit_to_user_mode+0x172/0x1b2 kernel/entry/common.c:268
>      entry_SYSCALL_64_after_hwframe+0x61/0xc6
>      RIP: 0033:0x78e38575e1db
>      Code: 0f 05 48 3d 00 f0 ff ff 77 45 c3 0f 1f 40 00 48 83 ec 18 89
>      7c 24 0c e8 63 fc ff ff 8b 7c 24 0c 41 89 c0 b8 03 00 00 00 0f 05
>      <48> 3d 00 f0 ff ff 77 35 44 89 c7 89 44 24 0c e8 a1 fc ff ff 8b 44
>      RSP: 002b:00007ffffc20a0b0 EFLAGS: 00000293 ORIG_RAX:
>      0000000000000003
>      RAX: 0000000000000000 RBX: 0000000000000006 RCX: 000078e38575e1db
>      RDX: ffffffffffffffb8 RSI: 0000000020000000 RDI: 0000000000000005
>      RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000150
>      R10: 0000000000000000 R11: 0000000000000293 R12: 000000000000e155
>      R13: 00007ffffc20a140 R14: 00007ffffc20a130 R15: 00007ffffc20a0e8
>
>  include/net/bluetooth/hci.h |  1 +
>  net/bluetooth/hci_core.c    | 16 ++++++++++++++--
>  2 files changed, 15 insertions(+), 2 deletions(-)
>
> diff --git a/include/net/bluetooth/hci.h b/include/net/bluetooth/hci.h
> index e004ba04a9ae..36304c217151 100644
> --- a/include/net/bluetooth/hci.h
> +++ b/include/net/bluetooth/hci.h
> @@ -353,6 +353,7 @@ enum {
>         HCI_OFFLOAD_CODECS_ENABLED,
>         HCI_LE_SIMULTANEOUS_ROLES,
>         HCI_CMD_DRAIN_WORKQUEUE,
> +       HCI_SUSPEND_REGISTERED,
>
>         HCI_MESH_EXPERIMENTAL,
>         HCI_MESH,
> diff --git a/net/bluetooth/hci_core.c b/net/bluetooth/hci_core.c
> index 66c7cdba0d32..5a32d17c69b8 100644
> --- a/net/bluetooth/hci_core.c
> +++ b/net/bluetooth/hci_core.c
> @@ -2760,10 +2760,18 @@ int hci_register_suspend_notifier(struct hci_dev *hdev)
>  {
>         int ret = 0;
>
> -       if (!test_bit(HCI_QUIRK_NO_SUSPEND_NOTIFIER, &hdev->quirks)) {
> +       hci_dev_lock(hdev);
> +       if (!test_bit(HCI_QUIRK_NO_SUSPEND_NOTIFIER, &hdev->quirks) &&
> +           !hci_dev_test_and_set_flag(hdev, HCI_SUSPEND_REGISTERED)) {
> +               memset(&hdev->suspend_notifier, 0,
> +                      sizeof(hdev->suspend_notifier));
>                 hdev->suspend_notifier.notifier_call = hci_suspend_notifier;
>                 ret = register_pm_notifier(&hdev->suspend_notifier);
> +
> +               if (ret)
> +                       hci_dev_clear_flag(hdev, HCI_SUSPEND_REGISTERED);
>         }
> +       hci_dev_unlock(hdev);
>
>         return ret;
>  }
> @@ -2772,8 +2780,12 @@ int hci_unregister_suspend_notifier(struct hci_dev *hdev)
>  {
>         int ret = 0;
>
> -       if (!test_bit(HCI_QUIRK_NO_SUSPEND_NOTIFIER, &hdev->quirks))
> +       hci_dev_lock(hdev);
> +       if (!test_bit(HCI_QUIRK_NO_SUSPEND_NOTIFIER, &hdev->quirks) &&
> +           hci_dev_test_and_clear_flag(hdev, HCI_SUSPEND_REGISTERED)) {
>                 ret = unregister_pm_notifier(&hdev->suspend_notifier);
> +       }
> +       hci_dev_unlock(hdev);
>
>         return ret;
>  }

Perhaps it would have been better to stop calling these on hci_sock.c
and just make the notifier callback check
hci_dev_test_and_set_flag(hdev, HCI_USER_CHANNEL) return NOTIFY_DONE.

> --
> 2.37.3.998.g577e59143f-goog
>


-- 
Luiz Augusto von Dentz