[PATCH 1/2] nvmet-pci: validate queue IDs against endpoint queues

[Michael Bommarito <michael.bommarito@gmail.com>]

The NVMe PCI endpoint transport allocates SQ/CQ arrays using
ctrl->nr_queues, which is capped by endpoint interrupt capacity. Common
target admin validation only checks queue IDs against subsys->max_qid, so
a root-complex host can submit Create/Delete SQ/CQ commands with qids that
pass the common checks but index past the smaller endpoint transport
arrays.

Impact: A PCI root-complex host can crash an NVMe PCI endpoint target with
malformed queue IDs.

Reject queue IDs that are outside ctrl->nr_queues before indexing the
endpoint SQ/CQ arrays.

Fixes: 0faa0fe6f90e ("nvmet: New NVMe PCI endpoint function target driver")
Cc: stable@vger.kernel.org
Assisted-by: Codex:gpt-5-5-xhigh
Signed-off-by: Michael Bommarito <michael.bommarito@gmail.com>
---

I reproduced this with a same-translation-unit KUnit/KASAN test. The stock
Create CQ path faults in nvmet_pci_epf_create_cq() after
nvmet_check_io_cqid() accepts qid 2 with max_qid 8 and nr_queues 2. The
patched checks reject malformed Create/Delete SQ/CQ cases while the benign
control still passes.
 drivers/nvme/target/pci-epf.c | 31 ++++++++++++++++++++++++++-----
 1 file changed, 26 insertions(+), 5 deletions(-)

diff --git a/drivers/nvme/target/pci-epf.c b/drivers/nvme/target/pci-epf.c
index 4e9db96ebfecd..5bddda09c0538 100644
--- a/drivers/nvme/target/pci-epf.c
+++ b/drivers/nvme/target/pci-epf.c
@@ -1267,10 +1267,15 @@ static u16 nvmet_pci_epf_create_cq(struct nvmet_ctrl *tctrl,
 		u16 cqid, u16 flags, u16 qsize, u64 pci_addr, u16 vector)
 {
 	struct nvmet_pci_epf_ctrl *ctrl = tctrl->drvdata;
-	struct nvmet_pci_epf_queue *cq = &ctrl->cq[cqid];
+	struct nvmet_pci_epf_queue *cq;
 	u16 status;
 	int ret;
 
+	if (cqid >= ctrl->nr_queues)
+		return NVME_SC_QID_INVALID | NVME_STATUS_DNR;
+
+	cq = &ctrl->cq[cqid];
+
 	if (test_bit(NVMET_PCI_EPF_Q_LIVE, &cq->flags))
 		return NVME_SC_QID_INVALID | NVME_STATUS_DNR;
 
@@ -1348,7 +1353,12 @@ static u16 nvmet_pci_epf_create_cq(struct nvmet_ctrl *tctrl,
 static u16 nvmet_pci_epf_delete_cq(struct nvmet_ctrl *tctrl, u16 cqid)
 {
 	struct nvmet_pci_epf_ctrl *ctrl = tctrl->drvdata;
-	struct nvmet_pci_epf_queue *cq = &ctrl->cq[cqid];
+	struct nvmet_pci_epf_queue *cq;
+
+	if (cqid >= ctrl->nr_queues)
+		return NVME_SC_QID_INVALID | NVME_STATUS_DNR;
+
+	cq = &ctrl->cq[cqid];
 
 	if (!test_and_clear_bit(NVMET_PCI_EPF_Q_LIVE, &cq->flags))
 		return NVME_SC_QID_INVALID | NVME_STATUS_DNR;
@@ -1367,10 +1377,16 @@ static u16 nvmet_pci_epf_create_sq(struct nvmet_ctrl *tctrl,
 		u16 sqid, u16 cqid, u16 flags, u16 qsize, u64 pci_addr)
 {
 	struct nvmet_pci_epf_ctrl *ctrl = tctrl->drvdata;
-	struct nvmet_pci_epf_queue *sq = &ctrl->sq[sqid];
-	struct nvmet_pci_epf_queue *cq = &ctrl->cq[cqid];
+	struct nvmet_pci_epf_queue *sq;
+	struct nvmet_pci_epf_queue *cq;
 	u16 status;
 
+	if (sqid >= ctrl->nr_queues || cqid >= ctrl->nr_queues)
+		return NVME_SC_QID_INVALID | NVME_STATUS_DNR;
+
+	sq = &ctrl->sq[sqid];
+	cq = &ctrl->cq[cqid];
+
 	if (test_bit(NVMET_PCI_EPF_Q_LIVE, &sq->flags))
 		return NVME_SC_QID_INVALID | NVME_STATUS_DNR;
 
@@ -1419,7 +1435,12 @@ static u16 nvmet_pci_epf_create_sq(struct nvmet_ctrl *tctrl,
 static u16 nvmet_pci_epf_delete_sq(struct nvmet_ctrl *tctrl, u16 sqid)
 {
 	struct nvmet_pci_epf_ctrl *ctrl = tctrl->drvdata;
-	struct nvmet_pci_epf_queue *sq = &ctrl->sq[sqid];
+	struct nvmet_pci_epf_queue *sq;
+
+	if (sqid >= ctrl->nr_queues)
+		return NVME_SC_QID_INVALID | NVME_STATUS_DNR;
+
+	sq = &ctrl->sq[sqid];
 
 	if (!test_and_clear_bit(NVMET_PCI_EPF_Q_LIVE, &sq->flags))
 		return NVME_SC_QID_INVALID | NVME_STATUS_DNR;
-- 
2.53.0