[PATCH rdma] RDMA/qedr: Fix KASAN: use-after-free in ucma_event_handler+0x532

[Michal Kalderon <michal.kalderon@marvell.com>]

Private data passed to iwarp_cm_handler is copied for
connection request / response, but ignored otherwise.
If junk is passed, it is stored in the event and used later
in the event processing.
Driver passed old junk pointer during connection close
which lead to a use-after-free on event processing.
Set private data to NULL for events that don 't have private
data.

BUG: KASAN: use-after-free in ucma_event_handler+0x532/0x560 [rdma_ucm]
kernel: Read of size 4 at addr ffff8886caa71200 by task kworker/u128:1/5250
kernel:
kernel: Workqueue: iw_cm_wq cm_work_handler [iw_cm]
kernel: Call Trace:
kernel: dump_stack+0x8c/0xc0
kernel: print_address_description.constprop.0+0x1b/0x210
kernel: ? ucma_event_handler+0x532/0x560 [rdma_ucm]
kernel: ? ucma_event_handler+0x532/0x560 [rdma_ucm]
kernel: __kasan_report.cold+0x1a/0x33
kernel: ? ucma_event_handler+0x532/0x560 [rdma_ucm]
kernel: kasan_report+0xe/0x20
kernel: check_memory_region+0x130/0x1a0
kernel: memcpy+0x20/0x50
kernel: ucma_event_handler+0x532/0x560 [rdma_ucm]
kernel: ? __rpc_execute+0x608/0x620 [sunrpc]
kernel: cma_iw_handler+0x212/0x330 [rdma_cm]
kernel: ? iw_conn_req_handler+0x6e0/0x6e0 [rdma_cm]
kernel: ? enqueue_timer+0x86/0x140
kernel: ? _raw_write_lock_irq+0xd0/0xd0
kernel: cm_work_handler+0xd3d/0x1070 [iw_cm]

Fixes: e411e0587e0d ("RDMA/qedr: Add iWARP connection management functions")
Signed-off-by: Ariel Elior <ariel.elior@marvell.com>
Signed-off-by: Michal Kalderon <michal.kalderon@marvell.com>
---
 drivers/infiniband/hw/qedr/qedr_iw_cm.c | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/drivers/infiniband/hw/qedr/qedr_iw_cm.c b/drivers/infiniband/hw/qedr/qedr_iw_cm.c
index 792eecd206b6..97fc7dd353b0 100644
--- a/drivers/infiniband/hw/qedr/qedr_iw_cm.c
+++ b/drivers/infiniband/hw/qedr/qedr_iw_cm.c
@@ -150,8 +150,17 @@ qedr_iw_issue_event(void *context,
 	if (params->cm_info) {
 		event.ird = params->cm_info->ird;
 		event.ord = params->cm_info->ord;
-		event.private_data_len = params->cm_info->private_data_len;
-		event.private_data = (void *)params->cm_info->private_data;
+		/* Only connect_request and reply have valid private data
+		 * the rest of the events this may be left overs from
+		 * connection establishment. CONNECT_REQUEST is issued via
+		 * qedr_iw_mpa_request
+		 */
+		if (event_type == IW_CM_EVENT_CONNECT_REPLY) {
+			event.private_data_len =
+				params->cm_info->private_data_len;
+			event.private_data =
+				(void *)params->cm_info->private_data;
+		}
 	}
 
 	if (ep->cm_id)
-- 
2.14.5