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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org,
        "Belanger, Martin" <Martin.Belanger@dell.com>,
        Sagi Grimberg <sagi@grimberg.me>,
        Christoph Hellwig <hch@lst.de>
Subject: [PATCH 5.4 20/60] nvme-tcp: fix a NULL deref when receiving a 0-length r2t PDU
Date:   Mon, 22 Mar 2021 13:28:08 +0100
Message-Id: <20210322121923.049916383@linuxfoundation.org>
In-Reply-To: <20210322121922.372583154@linuxfoundation.org>
References: <20210322121922.372583154@linuxfoundation.org>
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From: Sagi Grimberg <sagi@grimberg.me>

commit fd0823f405090f9f410fc3e3ff7efb52e7b486fa upstream.

When the controller sends us a 0-length r2t PDU we should not attempt to
try to set up a h2cdata PDU but rather conclude that this is a buggy
controller (forward progress is not possible) and simply fail it
immediately.

Fixes: 3f2304f8c6d6 ("nvme-tcp: add NVMe over TCP host driver")
Reported-by: Belanger, Martin <Martin.Belanger@dell.com>
Signed-off-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/nvme/host/tcp.c |    7 +++++++
 1 file changed, 7 insertions(+)

--- a/drivers/nvme/host/tcp.c
+++ b/drivers/nvme/host/tcp.c
@@ -512,6 +512,13 @@ static int nvme_tcp_setup_h2c_data_pdu(s
 	req->pdu_len = le32_to_cpu(pdu->r2t_length);
 	req->pdu_sent = 0;
 
+	if (unlikely(!req->pdu_len)) {
+		dev_err(queue->ctrl->ctrl.device,
+			"req %d r2t len is %u, probably a bug...\n",
+			rq->tag, req->pdu_len);
+		return -EPROTO;
+	}
+
 	if (unlikely(req->data_sent + req->pdu_len > req->data_len)) {
 		dev_err(queue->ctrl->ctrl.device,
 			"req %d r2t len %u exceeded data len %u (%zu sent)\n",