nvme-tcp: fix potential memory corruption in nvme_tcp_recv_pdu()

jira VULN-56028
cve CVE-2025-21927
commit-author Maurizio Lombardi <mlombard@redhat.com>
commit ad95bab
upstream-diff Removed `nvme_tcp_c2h_term' case from
              `nvme_tcp_recv_pdu_supported' for the sake of consistency of
              `nvme_tcp_recv_pdu''s behavior relative to the upstream
              version, between the cases of proper and improper
              header. (What could be considered as "`c2h_term' type support"
              started with 84e0090 commit,
              not included in `ciqlts9_2''s history, so
              `nvme_tcp_recv_pdu_supported' in `ciqlts9_2' shouldn't report
              the `nvme_tcp_c2h_term' type as supported.)

nvme_tcp_recv_pdu() doesn't check the validity of the header length.
When header digests are enabled, a target might send a packet with an
invalid header length (e.g. 255), causing nvme_tcp_verify_hdgst()
to access memory outside the allocated area and cause memory corruptions
by overwriting it with the calculated digest.

Fix this by rejecting packets with an unexpected header length.

Fixes: 3f2304f ("nvme-tcp: add NVMe over TCP host driver")
	Signed-off-by: Maurizio Lombardi <mlombard@redhat.com>
	Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
	Signed-off-by: Keith Busch <kbusch@kernel.org>
(cherry picked from commit ad95bab)
	Signed-off-by: Marcin Wcisło <marcin.wcislo@conclusive.pl>

Author: pvts-mat

drivers/nvme/host/tcp.c

@@ -189,6 +189,18 @@ static inline int nvme_tcp_queue_id(struct nvme_tcp_queue *queue)
 	return queue - queue->ctrl->queues;
 }
 
+static inline bool nvme_tcp_recv_pdu_supported(enum nvme_tcp_pdu_type type)
+{
+	switch (type) {
+	case nvme_tcp_c2h_data:
+	case nvme_tcp_r2t:
+	case nvme_tcp_rsp:
+		return true;
+	default:
+		return false;
+	}
+}
+
 static inline struct blk_mq_tags *nvme_tcp_tagset(struct nvme_tcp_queue *queue)
 {
 	u32 queue_idx = nvme_tcp_queue_id(queue);
@@ -716,6 +728,16 @@ static int nvme_tcp_recv_pdu(struct nvme_tcp_queue *queue, struct sk_buff *skb,
 		return 0;
 
 	hdr = queue->pdu;
+	if (unlikely(hdr->hlen != sizeof(struct nvme_tcp_rsp_pdu))) {
+		if (!nvme_tcp_recv_pdu_supported(hdr->type))
+			goto unsupported_pdu;
+
+		dev_err(queue->ctrl->ctrl.device,
+			"pdu type %d has unexpected header length (%d)\n",
+			hdr->type, hdr->hlen);
+		return -EPROTO;
+	}
+
 	if (queue->hdr_digest) {
 		ret = nvme_tcp_verify_hdgst(queue, queue->pdu, hdr->hlen);
 		if (unlikely(ret))
@@ -739,10 +761,13 @@ static int nvme_tcp_recv_pdu(struct nvme_tcp_queue *queue, struct sk_buff *skb,
 		nvme_tcp_init_recv_ctx(queue);
 		return nvme_tcp_handle_r2t(queue, (void *)queue->pdu);
 	default:
-		dev_err(queue->ctrl->ctrl.device,
-			"unsupported pdu type (%d)\n", hdr->type);
-		return -EINVAL;
+		goto unsupported_pdu;
 	}
+
+unsupported_pdu:
+	dev_err(queue->ctrl->ctrl.device,
+		"unsupported pdu type (%d)\n", hdr->type);
+	return -EINVAL;
 }
 
 static inline void nvme_tcp_end_request(struct request *rq, u16 status)