[PATCH 1/1] nvme pci: fix the check of the cqe->command_id

[m.misono760@gmail.com (Masanori Misono)]

nvme_pci_submit_async_event() sets the command_id as
NVME_AQ_BLK_MQ_DEPTH. So only call nvme_complete_async_event()
if the cqe->command_is exactly matches the value.

If the cqe->command_id is invalid due to the hardware bug,
blk_mq_tag_to_rq() returns NULL. Check that value to prevent NULL
pointer dereference. Remove the duplicate check if the command_id
is bigger than or equal to the nvmeq->q_depth.

Signed-off-by: Masanori Misono <m.misono760 at gmail.com>
---
 drivers/nvme/host/pci.c | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c
index c33bb201b884..cc6bb7abb752 100644
--- a/drivers/nvme/host/pci.c
+++ b/drivers/nvme/host/pci.c
@@ -878,13 +878,6 @@ static inline void nvme_handle_cqe(struct nvme_queue *nvmeq, u16 idx)
 	volatile struct nvme_completion *cqe = &nvmeq->cqes[idx];
 	struct request *req;
 
-	if (unlikely(cqe->command_id >= nvmeq->q_depth)) {
-		dev_warn(nvmeq->dev->ctrl.device,
-			"invalid id %d completed on queue %d\n",
-			cqe->command_id, le16_to_cpu(cqe->sq_id));
-		return;
-	}
-
 	/*
 	 * AEN requests are special as they don't time out and can
 	 * survive any kind of queue freeze and often don't respond to
@@ -892,13 +885,20 @@ static inline void nvme_handle_cqe(struct nvme_queue *nvmeq, u16 idx)
 	 * for them but rather special case them here.
 	 */
 	if (unlikely(nvmeq->qid == 0 &&
-			cqe->command_id >= NVME_AQ_BLK_MQ_DEPTH)) {
+			cqe->command_id == NVME_AQ_BLK_MQ_DEPTH)) {
 		nvme_complete_async_event(&nvmeq->dev->ctrl,
 				cqe->status, &cqe->result);
 		return;
 	}
 
 	req = blk_mq_tag_to_rq(*nvmeq->tags, cqe->command_id);
+	if (unlikely(req == NULL)) {
+		dev_warn(nvmeq->dev->ctrl.device,
+			"invalid id %d completed on queue %d\n",
+			cqe->command_id, le16_to_cpu(cqe->sq_id));
+		return;
+	}
+
 	nvme_end_request(req, cqe->status, cqe->result);
 }
 
-- 
2.17.1