Commit dd7d37cc authored by Chen Ridong's avatar Chen Ridong Committed by Herbert Xu
Browse files

padata: avoid UAF for reorder_work 



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

crypto_request			crypto_request		crypto_del_alg
padata_do_serial
  ...
  padata_reorder
    // processes all remaining
    // requests then breaks
    while (1) {
      if (!padata)
        break;
      ...
    }

				padata_do_serial
				  // new request added
				  list_add
    // sees the new request
    queue_work(reorder_work)
				  padata_reorder
				    queue_work_on(squeue->work)
...

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

							crypto_del_alg
							  // free pd

<kworker context>
invoke_padata_reorder
  // UAF of pd

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

Fixes: bbefa1dd ("crypto: pcrypt - Avoid deadlock by using per-instance padata queues")
Signed-off-by: default avatarChen Ridong <chenridong@huawei.com>
Acked-by: default avatarDaniel Jordan <daniel.m.jordan@oracle.com>
Signed-off-by: default avatarHerbert Xu <herbert@gondor.apana.org.au>
parent e01780ea

kernel/padata.c

+9 −1
Original line number Diff line number Diff line
@@ -352,9 +352,15 @@ static void padata_reorder(struct parallel_data *pd) 
	smp_mb();



	reorder = per_cpu_ptr(pd->reorder_list, pd->cpu);

	if (!list_empty(&reorder->list) && padata_find_next(pd, false))

	if (!list_empty(&reorder->list) && padata_find_next(pd, false)) {

		/*

		 * Other context(eg. the padata_serial_worker) can finish the request.

		 * To avoid UAF issue, add pd ref here, and put pd ref after reorder_work finish.

		 */

		padata_get_pd(pd);

		queue_work(pinst->serial_wq, &pd->reorder_work);

	}

}



static void invoke_padata_reorder(struct work_struct *work)

{
@@ -364,6 +370,8 @@ static void invoke_padata_reorder(struct work_struct *work) 
	pd = container_of(work, struct parallel_data, reorder_work);

	padata_reorder(pd);

	local_bh_enable();

	/* Pairs with putting the reorder_work in the serial_wq */

	padata_put_pd(pd);

}



static void padata_serial_worker(struct work_struct *serial_work)