[PATCH] nvme-rdma: Avoid double freeing of async event data

[Prabhath Sajeepa]

The timeout of identify cmd, which is invoked as part of admin queue
creation, can result in freeing of async event data both in
nvme_rdma_timeout handler and error handling path of
nvme_rdma_configure_admin queue thus causing NULL pointer reference.
Call Trace:
 ? nvme_rdma_setup_ctrl+0x223/0x800 [nvme_rdma]
 nvme_rdma_create_ctrl+0x2ba/0x3f7 [nvme_rdma]
 nvmf_dev_write+0xa54/0xcc6 [nvme_fabrics]
 __vfs_write+0x1b/0x40
 vfs_write+0xb2/0x1b0
 ksys_write+0x61/0xd0
 __x64_sys_write+0x1a/0x20
 do_syscall_64+0x60/0x1e0
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Signed-off-by: Prabhath Sajeepa <psajeepa@xxxxxxxxxxxxxxx>
Reviewed-by: Roland Dreier <roland@xxxxxxxxxxxxxxx>
---
 drivers/nvme/host/rdma.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/nvme/host/rdma.c b/drivers/nvme/host/rdma.c
index 3e85c5c..0fe08c4 100644
--- a/drivers/nvme/host/rdma.c
+++ b/drivers/nvme/host/rdma.c
@@ -850,9 +850,11 @@ static int nvme_rdma_configure_admin_queue(struct nvme_rdma_ctrl *ctrl,
 	if (new)
 		blk_mq_free_tag_set(ctrl->ctrl.admin_tagset);
 out_free_async_qe:
-	nvme_rdma_free_qe(ctrl->device->dev, &ctrl->async_event_sqe,
-		sizeof(struct nvme_command), DMA_TO_DEVICE);
-	ctrl->async_event_sqe.data = NULL;
+	if (ctrl->async_event_sqe.data) {
+		nvme_rdma_free_qe(ctrl->device->dev, &ctrl->async_event_sqe,
+			sizeof(struct nvme_command), DMA_TO_DEVICE);
+		ctrl->async_event_sqe.data = NULL;
+	}
 out_free_queue:
 	nvme_rdma_free_queue(&ctrl->queues[0]);
 	return error;
-- 
2.7.4