nvme-tcp: sanitize request list handling

JIRA: https://issues.redhat.com/browse/RHEL-103236
CVE: CVE-2025-38264

commit 0bf04c8
Author: Hannes Reinecke <hare@kernel.org>
Date:   Wed May 28 08:45:33 2025 +0200

    nvme-tcp: sanitize request list handling

    Validate the request in nvme_tcp_handle_r2t() to ensure it's not part of
    any list, otherwise a malicious R2T PDU might inject a loop in request
    list processing.

    Signed-off-by: Hannes Reinecke <hare@kernel.org>
    Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
    Signed-off-by: Christoph Hellwig <hch@lst.de>

Signed-off-by: CKI Backport Bot <cki-ci-bot+cki-gitlab-backport-bot@redhat.com>

Author: CKI Backport Bot

drivers/nvme/host/tcp.c

@@ -453,7 +453,8 @@ nvme_tcp_fetch_request(struct nvme_tcp_queue *queue)
 			return NULL;
 	}
 
-	list_del(&req->entry);
+	list_del_init(&req->entry);
+	init_llist_node(&req->lentry);
 	return req;
 }
 
@@ -561,6 +562,8 @@ static int nvme_tcp_init_request(struct blk_mq_tag_set *set,
 	req->queue = queue;
 	nvme_req(rq)->ctrl = &ctrl->ctrl;
 	nvme_req(rq)->cmd = &pdu->cmd;
+	init_llist_node(&req->lentry);
+	INIT_LIST_HEAD(&req->entry);
 
 	return 0;
 }
@@ -765,6 +768,14 @@ static int nvme_tcp_handle_r2t(struct nvme_tcp_queue *queue,
 		return -EPROTO;
 	}
 
+	if (llist_on_list(&req->lentry) ||
+	    !list_empty(&req->entry)) {
+		dev_err(queue->ctrl->ctrl.device,
+			"req %d unexpected r2t while processing request\n",
+			rq->tag);
+		return -EPROTO;
+	}
+
 	req->pdu_len = 0;
 	req->h2cdata_left = r2t_length;
 	req->h2cdata_offset = r2t_offset;
@@ -2583,6 +2594,8 @@ static void nvme_tcp_submit_async_event(struct nvme_ctrl *arg)
 	ctrl->async_req.offset = 0;
 	ctrl->async_req.curr_bio = NULL;
 	ctrl->async_req.data_len = 0;
+	init_llist_node(&ctrl->async_req.lentry);
+	INIT_LIST_HEAD(&ctrl->async_req.entry);
 
 	nvme_tcp_queue_request(&ctrl->async_req, true, true);
 }