linux-kernel - Re: [PATCH 03/14] cxl/mem: Find device capabilities

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Message-ID: <234711bf-c03f-9aca-e0b5-ca677add3ea@google.com>
Date:   Sat, 30 Jan 2021 15:51:49 -0800 (PST)
From:   David Rientjes <rientjes@...gle.com>
To:     Ben Widawsky <ben.widawsky@...el.com>
cc:     linux-cxl@...r.kernel.org, linux-acpi@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-nvdimm@...ts.01.org,
        linux-pci@...r.kernel.org, Bjorn Helgaas <helgaas@...nel.org>,
        Chris Browy <cbrowy@...ry-design.com>,
        Christoph Hellwig <hch@...radead.org>,
        Dan Williams <dan.j.williams@...el.com>,
        Ira Weiny <ira.weiny@...el.com>,
        Jon Masters <jcm@...masters.org>,
        Jonathan Cameron <Jonathan.Cameron@...wei.com>,
        Rafael Wysocki <rafael.j.wysocki@...el.com>,
        Randy Dunlap <rdunlap@...radead.org>,
        Vishal Verma <vishal.l.verma@...el.com>,
        daniel.lll@...baba-inc.com,
        "John Groves (jgroves)" <jgroves@...ron.com>,
        "Kelley, Sean V" <sean.v.kelley@...el.com>
Subject: Re: [PATCH 03/14] cxl/mem: Find device capabilities

On Fri, 29 Jan 2021, Ben Widawsky wrote:

> +static int cxl_mem_setup_mailbox(struct cxl_mem *cxlm)
> +{
> +	const int cap = cxl_read_mbox_reg32(cxlm, CXLDEV_MB_CAPS_OFFSET);
> +
> +	cxlm->mbox.payload_size =
> +		1 << CXL_GET_FIELD(cap, CXLDEV_MB_CAP_PAYLOAD_SIZE);
> +
> +	/* 8.2.8.4.3 */
> +	if (cxlm->mbox.payload_size < 256) {
> +		dev_err(&cxlm->pdev->dev, "Mailbox is too small (%zub)",
> +			cxlm->mbox.payload_size);
> +		return -ENXIO;
> +	}

Any reason not to check cxlm->mbox.payload_size > (1 << 20) as well and 
return ENXIO if true?