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s390/qeth: remove unused buffer->aob pointer

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Except for tracing, the pointer is not used.

At the same time, accessing it from qeth_qdio_output_handler() is racy:
whenever qeth_qdio_cq_handler() gets control, its call to
qeth_qdio_handle_aob() frees the AOB.

So the AOB pointer that qeth_qdio_output_handler() stores into 'buffer'
can go stale at any time, and trigger a use-after-free.

Signed-off-by: Julian Wiedmann <jwi@linux.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Julian Wiedmann 2018-07-11 17:42:39 +02:00 committed by David S. Miller
parent 3b346c1814
commit f67a43a73b
2 changed files with 0 additions and 8 deletions
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1
drivers/s390/net/qeth_core.h
View File

@ -465,7 +465,6 @@ struct qeth_qdio_out_buffer {
struct sk_buff_head skb_list;
int is_header[QDIO_MAX_ELEMENTS_PER_BUFFER];
struct qaob *aob;
struct qeth_qdio_out_q *q;
struct qeth_qdio_out_buffer *next_pending;
};

7
drivers/s390/net/qeth_core_main.c
View File

@ -473,7 +473,6 @@ static void qeth_cleanup_handled_pending(struct qeth_qdio_out_q *q, int bidx,
if (forced_cleanup && (atomic_read(&(q->bufs[bidx]->state)) ==
QETH_QDIO_BUF_HANDLED_DELAYED)) {
/* for recovery situations */
q->bufs[bidx]->aob = q->bufstates[bidx].aob;
qeth_init_qdio_out_buf(q, bidx);
QETH_CARD_TEXT(q->card, 2, "clprecov");
}
@ -510,7 +509,6 @@ static void qeth_qdio_handle_aob(struct qeth_card *card,
}
qeth_notify_skbs(buffer->q, buffer, notification);
buffer->aob = NULL;
/* Free dangling allocations. The attached skbs are handled by
* qeth_cleanup_handled_pending().
*/
@ -2478,7 +2476,6 @@ static int qeth_init_qdio_out_buf(struct qeth_qdio_out_q *q, int bidx)
skb_queue_head_init(&newbuf->skb_list);
lockdep_set_class(&newbuf->skb_list.lock, &qdio_out_skb_queue_key);
newbuf->q = q;
newbuf->aob = NULL;
newbuf->next_pending = q->bufs[bidx];
atomic_set(&newbuf->state, QETH_QDIO_BUF_EMPTY);
q->bufs[bidx] = newbuf;
@ -3735,11 +3732,7 @@ static void qeth_qdio_output_handler(struct ccw_device *ccwdev,
qeth_notify_skbs(queue, buffer,
TX_NOTIFY_PENDING);
}
buffer->aob = queue->bufstates[bidx].aob;
QETH_CARD_TEXT_(queue->card, 5, "pel%d", bidx);
QETH_CARD_TEXT(queue->card, 5, "aob");
QETH_CARD_TEXT_(queue->card, 5, "%lx",
virt_to_phys(buffer->aob));
/* prepare the queue slot for re-use: */
qeth_scrub_qdio_buffer(buffer->buffer,