In the Linux kernel, the following vulnerability has been resolved:
Bluetooth: When HCI work queue is drained, only queue chained work
The HCI command, event, and data packet processing workqueue is drained to avoid deadlock in commit 76727c02c1e1 ("Bluetooth: Call drain_workqueue() before resetting state").
There is another delayed work, which will queue command to this drained workqueue. Which results in the following error report:
Bluetooth: hci2: command 0x040f tx timeout WARNING: CPU: 1 PID: 18374 at kernel/workqueue.c:1438 queuework+0xdad/0x1140 Workqueue: events hcicmdtimeout RIP: 0010:queuework+0xdad/0x1140 RSP: 0000:ffffc90002cffc60 EFLAGS: 00010093 RAX: 0000000000000000 RBX: ffff8880b9d3ec00 RCX: 0000000000000000 RDX: ffff888024ba0000 RSI: ffffffff814e048d RDI: ffff8880b9d3ec08 RBP: 0000000000000008 R08: 0000000000000000 R09: 00000000b9d39700 R10: ffffffff814f73c6 R11: 0000000000000000 R12: ffff88807cce4c60 R13: 0000000000000000 R14: ffff8880796d8800 R15: ffff8880796d8800 FS: 0000000000000000(0000) GS:ffff8880b9d00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000000c0174b4000 CR3: 000000007cae9000 CR4: 00000000003506e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: <TASK> ? queueworkon+0xcb/0x110 ? lockdephardirqsoff+0x90/0xd0 queueworkon+0xee/0x110 processonework+0x996/0x1610 ? pwqdecnrinflight+0x2a0/0x2a0 ? rwlockbug.part.0+0x90/0x90 ? _rawspinlockirq+0x41/0x50 workerthread+0x665/0x1080 ? processonework+0x1610/0x1610 kthread+0x2e9/0x3a0 ? kthreadcompleteandexit+0x40/0x40 retfromfork+0x1f/0x30 </TASK>
To fix this, we can add a new HCIDRAINWQ flag, and don't queue the timeout workqueue while command workqueue is draining.