linux-kernel - [PATCH V2] nvme-rdma: fix double free in nvme_rdma_free

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Message-Id: <1525945328-1908-1-git-send-email-jianchao.w.wang@oracle.com>
Date:   Thu, 10 May 2018 17:42:08 +0800
From:   Jianchao Wang <jianchao.w.wang@...cle.com>
To:     keith.busch@...el.com, axboe@...com, hch@....de, sagi@...mberg.me
Cc:     linux-nvme@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: [PATCH V2] nvme-rdma: fix double free in nvme_rdma_free_queue

BUG: KASAN: double-free or invalid-free in nvme_rdma_free_queue+0xf6/0x110 [nvme_rdma]
Workqueue: nvme-reset-wq nvme_rdma_reset_ctrl_work [nvme_rdma]
Call Trace:
 dump_stack+0x91/0xeb
 print_address_description+0x6b/0x290
 kasan_report_invalid_free+0x55/0x80
 __kasan_slab_free+0x176/0x190
 kfree+0xeb/0x310
 nvme_rdma_free_queue+0xf6/0x110 [nvme_rdma]
 nvme_rdma_configure_admin_queue+0x1a3/0x4d0 [nvme_rdma]
 nvme_rdma_reset_ctrl_work+0x4e/0xd0 [nvme_rdma]
 process_one_work+0x3ca/0xaa0
 worker_thread+0x4e2/0x6c0
 kthread+0x18d/0x1e0
 ret_from_fork+0x24/0x30

The double free is on ctrl->async_event_sqe.
If any case fails before ctrl->async_event_sqe is allocated in
nvme_rdma_configure_admin_queue, nvme_rdma_free_queue will be
invoked. However, at the moment, the ctrl->async_event_sqe has
not been allocated because it has been freed in
nvme_rdma_reset_ctrl_work
  -> nvme_rdma_shutdown_ctrl
    ->nvme_rdma_destroy_admin_queue
      -> nvme_rdma_free_queue

Signed-off-by: Jianchao Wang <jianchao.w.wang@...cle.com>
---

V2:
handle it in nvme_rdma_free_queue and add some comment to explain it.

 drivers/nvme/host/rdma.c | 15 ++++++++++++---
 1 file changed, 12 insertions(+), 3 deletions(-)

diff --git a/drivers/nvme/host/rdma.c b/drivers/nvme/host/rdma.c
index 966e0dd..fa5cf87 100644
--- a/drivers/nvme/host/rdma.c
+++ b/drivers/nvme/host/rdma.c
@@ -561,9 +561,18 @@ static void nvme_rdma_free_queue(struct nvme_rdma_queue *queue)
 		return;
 
 	if (nvme_rdma_queue_idx(queue) == 0) {
-		nvme_rdma_free_qe(queue->device->dev,
-			&queue->ctrl->async_event_sqe,
-			sizeof(struct nvme_command), DMA_TO_DEVICE);
+		/*
+		 * async_event_sqe is not allocated in nvme_rdma_alloc_queue.
+		 * so there are cases where NVME_RDMA_Q_ALLOCATED is set, but
+		 * async_event_sqe is not allocated. To avoid double free, set
+		 * async_event_sqe.data to NULL to indicate it has been freed.
+		 */
+		if (queue->ctrl->async_event_sqe.data) {
+			nvme_rdma_free_qe(queue->device->dev,
+				&queue->ctrl->async_event_sqe,
+				sizeof(struct nvme_command), DMA_TO_DEVICE);
+			queue->ctrl->async_event_sqe.data = NULL;
+		}
 	}
 
 	nvme_rdma_destroy_queue_ib(queue);
-- 
2.7.4