[PATCH 5.14 306/432] nvme: code command_id with a genctr for use-after-free validation

Greg Kroah-Hartman
2021-09-16T17:44:46Z

From: Sagi Grimberg <sagi@grimberg.me>

[ Upstream commit e7006de6c23803799be000a5dcce4d916a36541a ]

We cannot detect a (perhaps buggy) controller that is sending us
a completion for a request that was already completed (for example
sending a completion twice), this phenomenon was seen in the wild
a few times.

So to protect against this, we use the upper 4 msbits of the nvme sqe
command_id to use as a 4-bit generation counter and verify it matches
the existing request generation that is incrementing on every execution.

The 16-bit command_id structure now is constructed by:
| xxxx | xxxxxxxxxxxx |
gen request tag

This means that we are giving up some possible queue depth as 12 bits
allow for a maximum queue depth of 4095 instead of 65536, however we
never create such long queues anyways so no real harm done.

Suggested-by: Keith Busch <kbusch@kernel.org>
Signed-off-by: Sagi Grimberg <sagi@grimberg.me>
Acked-by: Keith Busch <kbusch@kernel.org>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Daniel Wagner <dwagner@suse.de>
Tested-by: Daniel Wagner <dwagner@suse.de>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/nvme/host/core.c | 3 ++-
drivers/nvme/host/nvme.h | 47 +++++++++++++++++++++++++++++++++++++-
drivers/nvme/host/pci.c | 2 +-
drivers/nvme/host/rdma.c | 4 ++--
drivers/nvme/host/tcp.c | 26 ++++++++++-----------
drivers/nvme/target/loop.c | 4 ++--
6 files changed, 66 insertions(+), 20 deletions(-)

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index dfd9dec0c1f6..2f0cbaba12ac 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -1029,7 +1029,8 @@ blk_status_t nvme_setup_cmd(struct nvme_ns *ns, struct request *req)
return BLK_STS_IOERR;
}

- cmd->common.command_id = req->tag;
+ nvme_req(req)->genctr++;
+ cmd->common.command_id = nvme_cid(req);
trace_nvme_setup_cmd(req, cmd);
return ret;
}
diff --git a/drivers/nvme/host/nvme.h b/drivers/nvme/host/nvme.h
index 5cd1fa3b8464..26511794629b 100644
--- a/drivers/nvme/host/nvme.h
+++ b/drivers/nvme/host/nvme.h
@@ -158,6 +158,7 @@ enum nvme_quirks {
struct nvme_request {
struct nvme_command *cmd;
union nvme_result result;
+ u8 genctr;
u8 retries;
u8 flags;
u16 status;
@@ -497,6 +498,49 @@ struct nvme_ctrl_ops {
int (*get_address)(struct nvme_ctrl *ctrl, char *buf, int size);
};

+/*
+ * nvme command_id is constructed as such:
+ * | xxxx | xxxxxxxxxxxx |
+ * gen request tag
+ */
+#define nvme_genctr_mask(gen) (gen & 0xf)
+#define nvme_cid_install_genctr(gen) (nvme_genctr_mask(gen) << 12)
+#define nvme_genctr_from_cid(cid) ((cid & 0xf000) >> 12)
+#define nvme_tag_from_cid(cid) (cid & 0xfff)
+
+static inline u16 nvme_cid(struct request *rq)
+{
+ return nvme_cid_install_genctr(nvme_req(rq)->genctr) | rq->tag;
+}
+
+static inline struct request *nvme_find_rq(struct blk_mq_tags *tags,
+ u16 command_id)
+{
+ u8 genctr = nvme_genctr_from_cid(command_id);
+ u16 tag = nvme_tag_from_cid(command_id);
+ struct request *rq;
+
+ rq = blk_mq_tag_to_rq(tags, tag);
+ if (unlikely(!rq)) {
+ pr_err("could not locate request for tag %#x\n",
+ tag);
+ return NULL;
+ }
+ if (unlikely(nvme_genctr_mask(nvme_req(rq)->genctr) != genctr)) {
+ dev_err(nvme_req(rq)->ctrl->device,
+ "request %#x genctr mismatch (got %#x expected %#x)\n",
+ tag, genctr, nvme_genctr_mask(nvme_req(rq)->genctr));
+ return NULL;
+ }
+ return rq;
+}
+
+static inline struct request *nvme_cid_to_rq(struct blk_mq_tags *tags,
+ u16 command_id)
+{
+ return blk_mq_tag_to_rq(tags, nvme_tag_from_cid(command_id));
+}
+
#ifdef CONFIG_FAULT_INJECTION_DEBUG_FS
void nvme_fault_inject_init(struct nvme_fault_inject *fault_inj,
const char *dev_name);
@@ -594,7 +638,8 @@ static inline void nvme_put_ctrl(struct nvme_ctrl *ctrl)

static inline bool nvme_is_aen_req(u16 qid, __u16 command_id)
{
- return !qid && command_id >= NVME_AQ_BLK_MQ_DEPTH;
+ return !qid &&
+ nvme_tag_from_cid(command_id) >= NVME_AQ_BLK_MQ_DEPTH;
}

void nvme_complete_rq(struct request *req);
diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c
index 51852085239e..c246fdacba2e 100644
--- a/drivers/nvme/host/pci.c
+++ b/drivers/nvme/host/pci.c
@@ -1014,7 +1014,7 @@ static inline void nvme_handle_cqe(struct nvme_queue *nvmeq, u16 idx)
return;
}

- req = blk_mq_tag_to_rq(nvme_queue_tagset(nvmeq), command_id);
+ req = nvme_find_rq(nvme_queue_tagset(nvmeq), command_id);
if (unlikely(!req)) {
dev_warn(nvmeq->dev->ctrl.device,
"invalid id %d completed on queue %d\n",
diff --git a/drivers/nvme/host/rdma.c b/drivers/nvme/host/rdma.c
index 3bd9cbc80246..a68704e39084 100644
--- a/drivers/nvme/host/rdma.c
+++ b/drivers/nvme/host/rdma.c
@@ -1730,10 +1730,10 @@ static void nvme_rdma_process_nvme_rsp(struct nvme_rdma_queue *queue,
struct request *rq;
struct nvme_rdma_request *req;

- rq = blk_mq_tag_to_rq(nvme_rdma_tagset(queue), cqe->command_id);
+ rq = nvme_find_rq(nvme_rdma_tagset(queue), cqe->command_id);
if (!rq) {
dev_err(queue->ctrl->ctrl.device,
- "tag 0x%x on QP %#x not found\n",
+ "got bad command_id %#x on QP %#x\n",
cqe->command_id, queue->qp->qp_num);
nvme_rdma_error_recovery(queue->ctrl);
return;
diff --git a/drivers/nvme/host/tcp.c b/drivers/nvme/host/tcp.c
index f05892e2e6c4..48b70e5235a3 100644
--- a/drivers/nvme/host/tcp.c
+++ b/drivers/nvme/host/tcp.c
@@ -487,11 +487,11 @@ static int nvme_tcp_process_nvme_cqe(struct nvme_tcp_queue *queue,
{
struct request *rq;

- rq = blk_mq_tag_to_rq(nvme_tcp_tagset(queue), cqe->command_id);
+ rq = nvme_find_rq(nvme_tcp_tagset(queue), cqe->command_id);
if (!rq) {
dev_err(queue->ctrl->ctrl.device,
- "queue %d tag 0x%x not found\n",
- nvme_tcp_queue_id(queue), cqe->command_id);
+ "got bad cqe.command_id %#x on queue %d\n",
+ cqe->command_id, nvme_tcp_queue_id(queue));
nvme_tcp_error_recovery(&queue->ctrl->ctrl);
return -EINVAL;
}
@@ -508,11 +508,11 @@ static int nvme_tcp_handle_c2h_data(struct nvme_tcp_queue *queue,
{
struct request *rq;

- rq = blk_mq_tag_to_rq(nvme_tcp_tagset(queue), pdu->command_id);
+ rq = nvme_find_rq(nvme_tcp_tagset(queue), pdu->command_id);
if (!rq) {
dev_err(queue->ctrl->ctrl.device,
- "queue %d tag %#x not found\n",
- nvme_tcp_queue_id(queue), pdu->command_id);
+ "got bad c2hdata.command_id %#x on queue %d\n",
+ pdu->command_id, nvme_tcp_queue_id(queue));
return -ENOENT;
}

@@ -606,7 +606,7 @@ static int nvme_tcp_setup_h2c_data_pdu(struct nvme_tcp_request *req,
data->hdr.plen =
cpu_to_le32(data->hdr.hlen + hdgst + req->pdu_len + ddgst);
data->ttag = pdu->ttag;
- data->command_id = rq->tag;
+ data->command_id = nvme_cid(rq);
data->data_offset = cpu_to_le32(req->data_sent);
data->data_length = cpu_to_le32(req->pdu_len);
return 0;
@@ -619,11 +619,11 @@ static int nvme_tcp_handle_r2t(struct nvme_tcp_queue *queue,
struct request *rq;
int ret;

- rq = blk_mq_tag_to_rq(nvme_tcp_tagset(queue), pdu->command_id);
+ rq = nvme_find_rq(nvme_tcp_tagset(queue), pdu->command_id);
if (!rq) {
dev_err(queue->ctrl->ctrl.device,
- "queue %d tag %#x not found\n",
- nvme_tcp_queue_id(queue), pdu->command_id);
+ "got bad r2t.command_id %#x on queue %d\n",
+ pdu->command_id, nvme_tcp_queue_id(queue));
return -ENOENT;
}
req = blk_mq_rq_to_pdu(rq);
@@ -703,7 +703,7 @@ static int nvme_tcp_recv_data(struct nvme_tcp_queue *queue, struct sk_buff *skb,
{
struct nvme_tcp_data_pdu *pdu = (void *)queue->pdu;
struct request *rq =
- blk_mq_tag_to_rq(nvme_tcp_tagset(queue), pdu->command_id);
+ nvme_cid_to_rq(nvme_tcp_tagset(queue), pdu->command_id);
struct nvme_tcp_request *req = blk_mq_rq_to_pdu(rq);

while (true) {
@@ -796,8 +796,8 @@ static int nvme_tcp_recv_ddgst(struct nvme_tcp_queue *queue,
}

if (pdu->hdr.flags & NVME_TCP_F_DATA_SUCCESS) {
- struct request *rq = blk_mq_tag_to_rq(nvme_tcp_tagset(queue),
- pdu->command_id);
+ struct request *rq = nvme_cid_to_rq(nvme_tcp_tagset(queue),
+ pdu->command_id);

nvme_tcp_end_request(rq, NVME_SC_SUCCESS);
queue->nr_cqe++;
diff --git a/drivers/nvme/target/loop.c b/drivers/nvme/target/loop.c
index 3a17a7e26bbf..0285ccc7541f 100644
--- a/drivers/nvme/target/loop.c
+++ b/drivers/nvme/target/loop.c
@@ -107,10 +107,10 @@ static void nvme_loop_queue_response(struct nvmet_req *req)
} else {
struct request *rq;

- rq = blk_mq_tag_to_rq(nvme_loop_tagset(queue), cqe->command_id);
+ rq = nvme_find_rq(nvme_loop_tagset(queue), cqe->command_id);
if (!rq) {
dev_err(queue->ctrl->ctrl.device,
- "tag 0x%x on queue %d not found\n",
+ "got bad command_id %#x on queue %d\n",
cqe->command_id, nvme_loop_queue_idx(queue));
return;
}
--
2.30.2