In the Linux kernel, the following vulnerability has been resolved:
pds_core: fix use-after-free on workqueue during remove
In pdsc_remove(), the workqueue is destroyed before pdsc_teardown()
is called. This ordering allows two paths to queue work on the
destroyed workqueue:
-
If pdsc_teardown() -> pdsc_devcmd_reset() times out, the error
path in pdsc_devcmd_locked() queues health_work.
-
A NotifyQ event can trigger the ISR and queue work before free_irq()
is called in pdsc_teardown().
Fix by moving destroy_workqueue() after pdsc_teardown() so the
workqueue outlives every queuer; destroy_workqueue() then flushes any
work still pending.
Draining the queued work also requires ordering the teardown so the
resources that work touches are freed last:
-
In pdsc_qcq_free(), after freeing the interrupt, cancel_work_sync()
the queue's work and only then clear qcq->intx, so
pdsc_process_adminq()'s read of qcq->intx for interrupt-credit
return cannot race with the clear.
-
Free adminqcq before notifyqcq: the shared adminq ISR is released
when adminqcq is freed, and the adminq work accesses notifyqcq, so
both must be stopped before notifyqcq is freed.