3.16.61-rc1 review patch. If anyone has any objections, please let me know.
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From: Julian Wiedmann jwi@linux.ibm.com
commit ce28867fd20c23cd769e78b4d619c4755bf71a1c upstream.
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 jwi@linux.ibm.com Signed-off-by: David S. Miller davem@davemloft.net [bwh: Backported to 3.16: adjust context] Signed-off-by: Ben Hutchings ben@decadent.org.uk --- drivers/s390/net/qeth_core.h | 11 +++++++++++ drivers/s390/net/qeth_core_main.c | 22 ++++++++++++++++------ 2 files changed, 27 insertions(+), 6 deletions(-)
--- a/drivers/s390/net/qeth_core.h +++ b/drivers/s390/net/qeth_core.h @@ -844,6 +844,17 @@ 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; +} + static inline struct qeth_card *CARD_FROM_CDEV(struct ccw_device *cdev) { struct qeth_card *card = dev_get_drvdata(&((struct ccwgroup_device *) --- a/drivers/s390/net/qeth_core_main.c +++ b/drivers/s390/net/qeth_core_main.c @@ -65,9 +65,6 @@ static void qeth_notify_skbs(struct qeth 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; @@ -451,6 +448,7 @@ static inline void qeth_qdio_handle_aob( 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"); @@ -475,10 +473,18 @@ static inline void qeth_qdio_handle_aob( 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); }
@@ -3635,6 +3641,10 @@ void qeth_qdio_output_handler(struct ccw 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);