REDHAT-BUG-2348600: Medium severity linux_kernel vulnerability

In the Linux kernel, the following vulnerability has been resolved:

padata: avoid UAF for reorderwork

Although the previous patch can avoid ps and ps UAF for doserial, it can not avoid potential UAF issue for reorderwork. This issue can happen just as below:

cryptorequest cryptorequest cryptodelalg padatadoserial ... padatareorder // processes all remaining // requests then breaks while (1) { if (!padata) break; ... }

padatadoserial // new request added listadd // sees the new request queuework(reorderwork) padatareorder queueworkon(squeue->work) ...

<kworker context> padataserialworker // completes new request, // no more outstanding // requests

cryptodelalg // free pd

<kworker context> invokepadatareorder // UAF of pd

To avoid UAF for 'reorderwork', get 'pd' ref before put 'reorderwork' into the 'serialwq' and put 'pd' ref until the 'serialwq' finish.