From ce28867fd20c23cd769e78b4d619c4755bf71a1c Mon Sep 17 00:00:00 2001 From: Julian Wiedmann Date: Fri, 29 Jun 2018 19:45:53 +0200 Subject: 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: 0da9581ddb0f ("qeth: exploit asynchronous delivery of storage blocks") Signed-off-by: Julian Wiedmann Signed-off-by: David S. Miller --- drivers/s390/net/qeth_core.h | 11 +++++++++++ drivers/s390/net/qeth_core_main.c | 22 ++++++++++++++++------ 2 files changed, 27 insertions(+), 6 deletions(-) (limited to 'drivers') diff --git a/drivers/s390/net/qeth_core.h b/drivers/s390/net/qeth_core.h index 2a5fec55bf60..940fd7b558d3 100644 --- a/drivers/s390/net/qeth_core.h +++ b/drivers/s390/net/qeth_core.h @@ -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. diff --git a/drivers/s390/net/qeth_core_main.c b/drivers/s390/net/qeth_core_main.c index 9d9182ed8ac4..d20a69a3bc40 100644 --- a/drivers/s390/net/qeth_core_main.c +++ b/drivers/s390/net/qeth_core_main.c @@ -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); -- cgit v1.2.3