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s390/qeth: don't clobber buffer on async TX completion 

If qeth_qdio_output_handler() detects that a transmit requires async
completion, it replaces the pending buffer's metadata object
(qeth_qdio_out_buffer) so that this queue buffer can be re-used while
the data is pending completion.

Later when the CQ indicates async completion of such a metadata object,
qeth_qdio_cq_handler() tries to free any data associated with this
object (since HW has now completed the transfer). By calling
qeth_clear_output_buffer(), it erronously operates on the queue buffer
that _previously_ belonged to this transfer ... but which has been
potentially re-used several times by now.
This results in double-free's of the buffer's data, and failing
transmits as the buffer descriptor is scrubbed in mid-air.

The correct way of handling this situation is to
1. scrub the queue buffer when it is prepared for re-use, and
2. later obtain the data addresses from the async-completion notifier
   (ie. the AOB), instead of the queue buffer.

All this only affects qeth devices used for af_iucv HiperTransport.

Fixes: 0da9581ddb ("qeth: exploit asynchronous delivery of storage blocks")
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 2018-06-29 19:45:53 +02:00 committed by David S. Miller
parent 9d0a58fb97
commit ce28867fd2
2 changed files with 27 additions and 6 deletions
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11
drivers/s390/net/qeth_core.h
View File

@ -829,6 +829,17 @@ struct qeth_trap_id {
/*some helper functions*/
#define QETH_CARD_IFNAME(card) (((card)->dev)? (card)->dev->name : "")
static inline void qeth_scrub_qdio_buffer(struct qdio_buffer *buf,
unsigned int elements)
{
unsigned int i;
for (i = 0; i < elements; i++)
memset(&buf->element[i], 0, sizeof(struct qdio_buffer_element));
buf->element[14].sflags = 0;
buf->element[15].sflags = 0;
}
/**
* qeth_get_elements_for_range() - find number of SBALEs to cover range.
* @start: Start of the address range.

22
drivers/s390/net/qeth_core_main.c
View File

@ -73,9 +73,6 @@ static void qeth_notify_skbs(struct qeth_qdio_out_q *queue,
struct qeth_qdio_out_buffer *buf,
enum iucv_tx_notify notification);
static void qeth_release_skbs(struct qeth_qdio_out_buffer *buf);
static void qeth_clear_output_buffer(struct qeth_qdio_out_q *queue,
struct qeth_qdio_out_buffer *buf,
enum qeth_qdio_buffer_states newbufstate);
static int qeth_init_qdio_out_buf(struct qeth_qdio_out_q *, int);
struct workqueue_struct *qeth_wq;
@ -489,6 +486,7 @@ static void qeth_qdio_handle_aob(struct qeth_card *card,
struct qaob *aob;
struct qeth_qdio_out_buffer *buffer;
enum iucv_tx_notify notification;
unsigned int i;
aob = (struct qaob *) phys_to_virt(phys_aob_addr);
QETH_CARD_TEXT(card, 5, "haob");
@ -513,10 +511,18 @@ static void qeth_qdio_handle_aob(struct qeth_card *card,
qeth_notify_skbs(buffer->q, buffer, notification);
buffer->aob = NULL;
qeth_clear_output_buffer(buffer->q, buffer,
QETH_QDIO_BUF_HANDLED_DELAYED);
/* Free dangling allocations. The attached skbs are handled by
* qeth_cleanup_handled_pending().
*/
for (i = 0;
i < aob->sb_count && i < QETH_MAX_BUFFER_ELEMENTS(card);
i++) {
if (aob->sba[i] && buffer->is_header[i])
kmem_cache_free(qeth_core_header_cache,
(void *) aob->sba[i]);
}
atomic_set(&buffer->state, QETH_QDIO_BUF_HANDLED_DELAYED);
/* from here on: do not touch buffer anymore */
qdio_release_aob(aob);
}
@ -3759,6 +3765,10 @@ static void qeth_qdio_output_handler(struct ccw_device *ccwdev,
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,
QETH_MAX_BUFFER_ELEMENTS(card));
if (qeth_init_qdio_out_buf(queue, bidx)) {
QETH_CARD_TEXT(card, 2, "outofbuf");
qeth_schedule_recovery(card);