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Subject[PATCH] Bluetooth: fix kernel null pointer dereference error on suspend
BUG Call Trace:
queue_work_on+0x39/0x40
hci_adv_monitors_clear+0x71/0x90 [bluetooth]
hci_unregister_dev+0x18a/0x2f0 [bluetooth]
btusb_disconnect+0x68/0x150 [btusb]
usb_unbind_interface+0x7f/0x260
device_release_driver_internal+0xec/0x1b0
device_release_driver+0x12/0x20
bus_remove_device+0xe1/0x150
device_del+0x17d/0x3e0
usb_disable_device+0x9f/0x250
usb_disconnect+0xc6/0x270
hub_event+0x6da/0x18d0
process_one_work+0x20c/0x400
worker_thread+0x34/0x400

RIP: 0010:__queue_work+0x92/0x3f0

NULL deference occurs in hci_update_background_scan() while it tries
to queue_work on already destroyed workqueues.

Change hci_unregister_dev() to invoke destroy_workqueues after the
call to hci_adv_monitors_clear().

Signed-off-by: Vamshi K Sthambamkadi <vamshi.k.sthambamkadi@gmail.com>
---
net/bluetooth/hci_core.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/net/bluetooth/hci_core.c b/net/bluetooth/hci_core.c
index 7959b85..5577cf9 100644
--- a/net/bluetooth/hci_core.c
+++ b/net/bluetooth/hci_core.c
@@ -3795,9 +3795,6 @@ void hci_unregister_dev(struct hci_dev *hdev)
kfree_const(hdev->hw_info);
kfree_const(hdev->fw_info);

- destroy_workqueue(hdev->workqueue);
- destroy_workqueue(hdev->req_workqueue);
-
hci_dev_lock(hdev);
hci_bdaddr_list_clear(&hdev->blacklist);
hci_bdaddr_list_clear(&hdev->whitelist);
@@ -3815,6 +3812,9 @@ void hci_unregister_dev(struct hci_dev *hdev)
hci_blocked_keys_clear(hdev);
hci_dev_unlock(hdev);

+ destroy_workqueue(hdev->workqueue);
+ destroy_workqueue(hdev->req_workqueue);
+
hci_dev_put(hdev);

ida_simple_remove(&hci_index_ida, id);
--
2.7.4
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