s390/qeth: fix use-after-free in error path

The error path in qeth_alloc_qdio_buffers() that takes care of
cleaning up the Output Queues is buggy. It first frees the queue, but
then calls qeth_clear_outq_buffers() with that very queue struct.

Make the call to qeth_clear_outq_buffers() part of the free action
(in the correct order), and while at it fix the naming of the helper.

Fixes: 0da9581ddb0f ("qeth: exploit asynchronous delivery of storage blocks")
Signed-off-by: Julian Wiedmann <jwi@linux.ibm.com>
Reviewed-by: Alexandra Winter <wintera@linux.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/s390/net/qeth_core_main.c b/drivers/s390/net/qeth_core_main.c
index ca62e7d3ee934e5b94e1160539046760169744c7..30679bfc8a1baa840715c2bc2b64ea77ec3a6295 100644 (file)
--- a/drivers/s390/net/qeth_core_main.c
+++ b/drivers/s390/net/qeth_core_main.c
@@ -2395,11 +2395,12 @@ static int qeth_init_qdio_out_buf(struct qeth_qdio_out_q *q, int bidx)
        return 0;
 }
 
-static void qeth_free_qdio_out_buf(struct qeth_qdio_out_q *q)
+static void qeth_free_output_queue(struct qeth_qdio_out_q *q)
 {
        if (!q)
                return;
 
+       qeth_clear_outq_buffers(q, 1);
        qdio_free_buffers(q->qdio_bufs, QDIO_MAX_BUFFERS_PER_Q);
        kfree(q);
 }
@@ -2473,10 +2474,8 @@ out_freeoutqbufs:
                card->qdio.out_qs[i]->bufs[j] = NULL;
        }
 out_freeoutq:
-       while (i > 0) {
-               qeth_free_qdio_out_buf(card->qdio.out_qs[--i]);
-               qeth_clear_outq_buffers(card->qdio.out_qs[i], 1);
-       }
+       while (i > 0)
+               qeth_free_output_queue(card->qdio.out_qs[--i]);
        kfree(card->qdio.out_qs);
        card->qdio.out_qs = NULL;
 out_freepool:
@@ -2509,10 +2508,8 @@ static void qeth_free_qdio_buffers(struct qeth_card *card)
        qeth_free_buffer_pool(card);
        /* free outbound qdio_qs */
        if (card->qdio.out_qs) {
-               for (i = 0; i < card->qdio.no_out_queues; ++i) {
-                       qeth_clear_outq_buffers(card->qdio.out_qs[i], 1);
-                       qeth_free_qdio_out_buf(card->qdio.out_qs[i]);
-               }
+               for (i = 0; i < card->qdio.no_out_queues; i++)
+                       qeth_free_output_queue(card->qdio.out_qs[i]);
                kfree(card->qdio.out_qs);
                card->qdio.out_qs = NULL;
        }