[PATCH v5] nvmet-tcp: fix a segmentation fault during io parsing error

[Grupi, Elad]

Looks good to me.

Thanks,
Elad

-----Original Message-----
From: Hou Pu <houpu.main at gmail.com> 
Sent: Wednesday, 31 March 2021 12:13
To: houpu.main at gmail.com; Grupi, Elad
Cc: linux-nvme at lists.infradead.org; sagi at grimberg.me
Subject: [PATCH v5] nvmet-tcp: fix a segmentation fault during io parsing error


[EXTERNAL EMAIL] 

From: Elad Grupi <elad.grupi at dell.com>

In case there is an io that contains inline data and it goes to parsing error flow, command response will free command and iov before clearing the data on the socket buffer.
This will delay the command response until receive flow is completed.

Fixes: 872d26a391da ("nvmet-tcp: add NVMe over TCP target driver")
Signed-off-by: Elad Grupi <elad.grupi at dell.com>
Signed-off-by: Hou Pu <houpu.main at gmail.com>
---
 drivers/nvme/target/tcp.c | 39 +++++++++++++++++++++++++++++++--------
 1 file changed, 31 insertions(+), 8 deletions(-)

diff --git a/drivers/nvme/target/tcp.c b/drivers/nvme/target/tcp.c index d658c6e8263a..0759eef3f4da 100644
--- a/drivers/nvme/target/tcp.c
+++ b/drivers/nvme/target/tcp.c
@@ -525,11 +525,36 @@ static void nvmet_tcp_queue_response(struct nvmet_req *req)
 	struct nvmet_tcp_cmd *cmd =
 		container_of(req, struct nvmet_tcp_cmd, req);
 	struct nvmet_tcp_queue	*queue = cmd->queue;
+	struct nvme_sgl_desc *sgl;
+	u32 len;
+
+	if (unlikely(cmd == queue->cmd)) {
+		sgl = &cmd->req.cmd->common.dptr.sgl;
+		len = le32_to_cpu(sgl->length);
+
+		/*
+		 * Wait for inline data before processing the response.
+		 * Avoid using helpers, this might happen before
+		 * nvmet_req_init is completed.
+		 */
+		if (queue->rcv_state == NVMET_TCP_RECV_PDU &&
+		    len && len < cmd->req.port->inline_data_size &&
+		    nvme_is_write(cmd->req.cmd))
+			return;
+	}
 
 	llist_add(&cmd->lentry, &queue->resp_list);
 	queue_work_on(queue_cpu(queue), nvmet_tcp_wq, &cmd->queue->io_work);  }
 
+static void nvmet_tcp_execute_request(struct nvmet_tcp_cmd *cmd) {
+	if (unlikely(cmd->flags & NVMET_TCP_F_INIT_FAILED))
+		nvmet_tcp_queue_response(&cmd->req);
+	else
+		cmd->req.execute(&cmd->req);
+}
+
 static int nvmet_try_send_data_pdu(struct nvmet_tcp_cmd *cmd)  {
 	u8 hdgst = nvmet_tcp_hdgst_len(cmd->queue); @@ -961,7 +986,7 @@ static int nvmet_tcp_done_recv_pdu(struct nvmet_tcp_queue *queue)
 			le32_to_cpu(req->cmd->common.dptr.sgl.length));
 
 		nvmet_tcp_handle_req_failure(queue, queue->cmd, req);
-		return -EAGAIN;
+		return 0;
 	}
 
 	ret = nvmet_tcp_map_data(queue->cmd);
@@ -1104,10 +1129,8 @@ static int nvmet_tcp_try_recv_data(struct nvmet_tcp_queue *queue)
 		return 0;
 	}
 
-	if (!(cmd->flags & NVMET_TCP_F_INIT_FAILED) &&
-	    cmd->rbytes_done == cmd->req.transfer_len) {
-		cmd->req.execute(&cmd->req);
-	}
+	if (cmd->rbytes_done == cmd->req.transfer_len)
+		nvmet_tcp_execute_request(cmd);
 
 	nvmet_prepare_receive_pdu(queue);
 	return 0;
@@ -1144,9 +1167,9 @@ static int nvmet_tcp_try_recv_ddgst(struct nvmet_tcp_queue *queue)
 		goto out;
 	}
 
-	if (!(cmd->flags & NVMET_TCP_F_INIT_FAILED) &&
-	    cmd->rbytes_done == cmd->req.transfer_len)
-		cmd->req.execute(&cmd->req);
+	if (cmd->rbytes_done == cmd->req.transfer_len)
+		nvmet_tcp_execute_request(cmd);
+
 	ret = 0;
 out:
 	nvmet_prepare_receive_pdu(queue);
--
2.28.0