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Bluetooth: use hdev->workqueue when queuing hdev->{cmd,ncmd}_timer works

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syzbot is reporting attempt to schedule hdev->cmd_work work from system_wq
WQ into hdev->workqueue WQ which is under draining operation [1], for
commit c8efcc2589 ("workqueue: allow chained queueing during
destruction") does not allow such operation.

The check introduced by commit 877afadad2 ("Bluetooth: When HCI work
queue is drained, only queue chained work") was incomplete.

Use hdev->workqueue WQ when queuing hdev->{cmd,ncmd}_timer works because
hci_{cmd,ncmd}_timeout() calls queue_work(hdev->workqueue). Also, protect
the queuing operation with RCU read lock in order to avoid calling
queue_delayed_work() after cancel_delayed_work() completed.

Link: https://syzkaller.appspot.com/bug?extid=243b7d89777f90f7613b [1]
Reported-by: syzbot <syzbot+243b7d89777f90f7613b@syzkaller.appspotmail.com>
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Fixes: 877afadad2 ("Bluetooth: When HCI work queue is drained, only queue chained work")
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
This commit is contained in:
Tetsuo Handa 2022-09-02 20:23:48 +09:00 committed by Luiz Augusto von Dentz
parent 2d2cb3066f
commit deee93d13d
2 changed files with 17 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

15
net/bluetooth/hci_core.c
View File

@ -597,6 +597,15 @@ static int hci_dev_do_reset(struct hci_dev *hdev)
/* Cancel these to avoid queueing non-chained pending work */
hci_dev_set_flag(hdev, HCI_CMD_DRAIN_WORKQUEUE);
/* Wait for
*
* if (!hci_dev_test_flag(hdev, HCI_CMD_DRAIN_WORKQUEUE))
* queue_delayed_work(&hdev->{cmd,ncmd}_timer)
*
* inside RCU section to see the flag or complete scheduling.
*/
synchronize_rcu();
/* Explicitly cancel works in case scheduled after setting the flag. */
cancel_delayed_work(&hdev->cmd_timer);
cancel_delayed_work(&hdev->ncmd_timer);
@ -4063,12 +4072,14 @@ static void hci_cmd_work(struct work_struct *work)
if (res < 0)
__hci_cmd_sync_cancel(hdev, -res);
rcu_read_lock();
if (test_bit(HCI_RESET, &hdev->flags) ||
hci_dev_test_flag(hdev, HCI_CMD_DRAIN_WORKQUEUE))
cancel_delayed_work(&hdev->cmd_timer);
else
schedule_delayed_work(&hdev->cmd_timer,
HCI_CMD_TIMEOUT);
queue_delayed_work(hdev->workqueue, &hdev->cmd_timer,
HCI_CMD_TIMEOUT);
rcu_read_unlock();
} else {
skb_queue_head(&hdev->cmd_q, skb);
queue_work(hdev->workqueue, &hdev->cmd_work);

6
net/bluetooth/hci_event.c
View File

@ -3767,16 +3767,18 @@ static inline void handle_cmd_cnt_and_timer(struct hci_dev *hdev, u8 ncmd)
{
cancel_delayed_work(&hdev->cmd_timer);
rcu_read_lock();
if (!test_bit(HCI_RESET, &hdev->flags)) {
if (ncmd) {
cancel_delayed_work(&hdev->ncmd_timer);
atomic_set(&hdev->cmd_cnt, 1);
} else {
if (!hci_dev_test_flag(hdev, HCI_CMD_DRAIN_WORKQUEUE))
schedule_delayed_work(&hdev->ncmd_timer,
HCI_NCMD_TIMEOUT);
queue_delayed_work(hdev->workqueue, &hdev->ncmd_timer,
HCI_NCMD_TIMEOUT);
}
}
rcu_read_unlock();
}
static u8 hci_cc_le_read_buffer_size_v2(struct hci_dev *hdev, void *data,