[PATCH] Bluetooth: Prevent double register of suspend

[Abhishek Pandit-Subedi]

From: Abhishek Pandit-Subedi <abhishekpandit@xxxxxxxxxxxx>

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@xxxxxxxxxxxxxxxx>
Signed-off-by: Abhishek Pandit-Subedi <abhishekpandit@xxxxxxxxxxxx>
---
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;
 }
-- 
2.37.3.998.g577e59143f-goog