linux-hardening - Re: [PATCH v5 06/17] soc: qcom: Add Qualcomm APSS minidump kernel driver

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Date:   Mon, 11 Sep 2023 13:01:39 +0200
From:   Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
To:     Mukesh Ojha <quic_mojha@...cinc.com>, corbet@....net,
        agross@...nel.org, andersson@...nel.org, konrad.dybcio@...aro.org,
        robh+dt@...nel.org, krzysztof.kozlowski+dt@...aro.org,
        conor+dt@...nel.org, keescook@...omium.org, tony.luck@...el.com,
        gpiccoli@...lia.com, mathieu.poirier@...aro.org,
        catalin.marinas@....com, will@...nel.org, linus.walleij@...aro.org,
        andy.shevchenko@...il.com, vigneshr@...com, nm@...com,
        matthias.bgg@...il.com, kgene@...nel.org, alim.akhtar@...sung.com,
        bmasney@...hat.com, quic_tsoni@...cinc.com
Cc:     linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-msm@...r.kernel.org, linux-hardening@...r.kernel.org,
        linux-remoteproc@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-gpio@...r.kernel.org,
        linux-mediatek@...ts.infradead.org,
        linux-samsung-soc@...r.kernel.org, kernel@...cinc.com
Subject: Re: [PATCH v5 06/17] soc: qcom: Add Qualcomm APSS minidump kernel
 driver

On 09/09/2023 22:16, Mukesh Ojha wrote:
> Minidump is a best effort mechanism to collect useful and predefined
> data for first level of debugging on end user devices running on
> Qualcomm SoCs. It is built on the premise that System on Chip (SoC)
> or subsystem part of SoC crashes, due to a range of hardware and
> software bugs. Hence, the ability to collect accurate data is only
> a best-effort. The data collected could be invalid or corrupted,
> data collection itself could fail, and so on.

...

> +static int qcom_apss_md_table_init(struct minidump *md,
> +				   struct minidump_subsystem *mdss_toc)
> +{
> +	struct minidump_ss_data *mdss_data;
> +
> +	mdss_data = devm_kzalloc(md->dev, sizeof(*mdss_data), GFP_KERNEL);
> +	if (!mdss_data)
> +		return -ENOMEM;
> +
> +	mdss_data->md_ss_toc = mdss_toc;
> +	mdss_data->md_regions = devm_kcalloc(md->dev, MAX_NUM_ENTRIES,
> +					     sizeof(struct minidump_region),
> +					     GFP_KERNEL);
> +	if (!mdss_data->md_regions)
> +		return -ENOMEM;
> +
> +	mdss_toc = mdss_data->md_ss_toc;
> +	mdss_toc->regions_baseptr = cpu_to_le64(virt_to_phys(mdss_data->md_regions));
> +	mdss_toc->enabled = cpu_to_le32(MINIDUMP_SS_ENABLED);
> +	mdss_toc->status = cpu_to_le32(1);
> +	mdss_toc->region_count = cpu_to_le32(0);
> +
> +	/* Tell bootloader not to encrypt the regions of this subsystem */
> +	mdss_toc->encryption_status = cpu_to_le32(MINIDUMP_SS_ENCR_DONE);
> +	mdss_toc->encryption_required = cpu_to_le32(MINIDUMP_SS_ENCR_NOTREQ);
> +
> +	md->apss_data = mdss_data;
> +
> +	return 0;
> +}
> +
> +static int qcom_apss_minidump_probe(struct platform_device *pdev)
> +{
> +	struct minidump_global_toc *mdgtoc;
> +	struct minidump *md;
> +	size_t size;
> +	int ret;
> +
> +	md = devm_kzalloc(&pdev->dev, sizeof(struct minidump), GFP_KERNEL);

sizeof(*)

Didn't you get such comments already?


> +	if (!md)
> +		return -ENOMEM;
> +
> +	md->dev = &pdev->dev;
> +	mdgtoc = qcom_smem_get(QCOM_SMEM_HOST_ANY, SBL_MINIDUMP_SMEM_ID, &size);
> +	if (IS_ERR(mdgtoc)) {
> +		ret = PTR_ERR(mdgtoc);
> +		dev_err(md->dev, "Couldn't find minidump smem item: %d\n", ret);
> +		return ret;

The syntax is:
return dev_err_probe

> +	}
> +
> +	if (size < sizeof(*mdgtoc) || !mdgtoc->status) {
> +		dev_err(md->dev, "minidump table is not initialized: %d\n", ret);

ret is uninitialized here. Please use automated tools for checking your
code:
coccinelle, smatch and sparse

> +		return -EINVAL;
> +	}
> +
> +	mutex_init(&md->md_lock);
> +	ret = qcom_apss_md_table_init(md, &mdgtoc->subsystems[MINIDUMP_APSS_DESC]);
> +	if (ret) {
> +		dev_err(md->dev, "apss minidump initialization failed: %d\n", ret);
> +		return ret;
> +	}
> +
> +	/* First entry would be ELF header */
> +	ret = qcom_md_add_elfheader(md);
> +	if (ret) {
> +		dev_err(md->dev, "Failed to add elf header: %d\n", ret);
> +		memset(md->apss_data->md_ss_toc, 0, sizeof(struct minidump_subsystem));

Why do you need it?

> +		return ret;
> +	}
> +
> +	platform_set_drvdata(pdev, md);
> +
> +	return ret;
> +}
> +
> +static int qcom_apss_minidump_remove(struct platform_device *pdev)
> +{
> +	struct minidump *md = platform_get_drvdata(pdev);
> +	struct minidump_ss_data *mdss_data;
> +
> +	mdss_data = md->apss_data;
> +	memset(mdss_data->md_ss_toc, cpu_to_le32(0), sizeof(struct minidump_subsystem));

Why do you need it?

> +	md = NULL;

That's useless assignment.

> +
> +	return 0;
> +}
> +
> +static struct platform_driver qcom_minidump_driver = {
> +	.probe = qcom_apss_minidump_probe,
> +	.remove = qcom_apss_minidump_remove,
> +	.driver  = {
> +		.name = "qcom-minidump-smem",
> +	},
> +};
> +
> +module_platform_driver(qcom_minidump_driver);
> +
> +MODULE_DESCRIPTION("Qualcomm APSS minidump driver");
> +MODULE_LICENSE("GPL");
> +MODULE_ALIAS("platform:qcom-minidump-smem");

Add a proper ID table instead of re-inventing it with module aliases.

Best regards,
Krzysztof