In the Linux kernel, the following vulnerability has been resolved:
net: airoha: npu: cancel wdt_work after releasing the WDT IRQ
airoha_npu_remove() calls cancel_work_sync() on each core’s wdt_work,
but the watchdog IRQ that queues it is requested with devm_request_irq()
and is freed only after .remove() returns. airoha_npu_wdt_handler() can
therefore schedule_work() again once the cancel has returned. struct
airoha_npu, which contains the work, is devm_kzalloc()’d and is freed in
that same unwind, so the late work dereferences freed memory.
Register the work with devm_work_autocancel() before devm_request_irq()
and drop .remove(). Devres runs in reverse order, so the IRQ is freed
before cancel_work_sync(), including when probe fails. A cancel left in
.remove() cannot get that order. Initializing the work first also stops
a pending watchdog interrupt from queuing an uninitialized work item.
Probe currently calls INIT_WORK() only after devm_request_irq().
This issue was identified during our ongoing static-analysis research
while reviewing kernel code.
