Re: [PATCH 3/3 v6] virtio: vdpa: new SolidNET DPU driver.

[Nathan Chancellor <nathan@kernel.org>]

Hi Alvaro,

On Mon, Dec 19, 2022 at 10:35:11AM +0200, Alvaro Karsz wrote:
> This commit includes:
>  1) The driver to manage the controlplane over vDPA bus.
>  2) A HW monitor device to read health values from the DPU.
> 
> Signed-off-by: Alvaro Karsz <alvaro.karsz@solid-run.com>

<snip>

> +static int psnet_open_pf_bar(struct pci_dev *pdev, struct psnet *psnet)
> +{
> +	char name[25];
> +	int ret, i, mask = 0;
> +	/* We don't know which BAR will be used to communicate..
> +	 * We will map every bar with len > 0.
> +	 *
> +	 * Later, we will discover the BAR and unmap all other BARs.
> +	 */
> +	for (i = 0; i < PCI_STD_NUM_BARS; i++) {
> +		if (pci_resource_len(pdev, i))
> +			mask |= (1 << i);
> +	}
> +
> +	/* No BAR can be used.. */
> +	if (!mask) {
> +		SNET_ERR(pdev, "Failed to find a PCI BAR\n");
> +		return -ENODEV;
> +	}
> +
> +	snprintf(name, SNET_NAME_SIZE, "psnet[%s]-bars", pci_name(pdev));
> +	ret = pcim_iomap_regions(pdev, mask, name);
> +	if (ret) {
> +		SNET_ERR(pdev, "Failed to request and map PCI BARs\n");
> +		return ret;
> +	}
> +
> +	for (i = 0; i < PCI_STD_NUM_BARS; i++) {
> +		if (mask & (1 << i))
> +			psnet->bars[i] = pcim_iomap_table(pdev)[i];
> +	}
> +
> +	return 0;
> +}
> +
> +static int snet_open_vf_bar(struct pci_dev *pdev, struct snet *snet)
> +{
> +	char name[20];
> +	int ret;
> +
> +	snprintf(name, SNET_NAME_SIZE, "snet[%s]-bar", pci_name(pdev));
> +	/* Request and map BAR */
> +	ret = pcim_iomap_regions(pdev, BIT(snet->psnet->cfg.vf_bar), name);
> +	if (ret) {
> +		SNET_ERR(pdev, "Failed to request and map PCI BAR for a VF\n");
> +		return ret;
> +	}
> +
> +	snet->bar = pcim_iomap_table(pdev)[snet->psnet->cfg.vf_bar];
> +
> +	return 0;
> +}

This patch as commit 73a720b16fa1 ("virtio: vdpa: new SolidNET DPU
driver.") in next-20221220 causes the following clang warnings:

  drivers/vdpa/solidrun/snet_main.c:561:2: error: 'snprintf' size argument is too large; destination buffer has size 25, but size argument is 256 [-Werror,-Wfortify-source]
          snprintf(name, SNET_NAME_SIZE, "psnet[%s]-bars", pci_name(pdev));
          ^
  drivers/vdpa/solidrun/snet_main.c:581:2: error: 'snprintf' size argument is too large; destination buffer has size 20, but size argument is 256 [-Werror,-Wfortify-source]
          snprintf(name, SNET_NAME_SIZE, "snet[%s]-bar", pci_name(pdev));
          ^
  2 errors generated.

This does not appear to be a false positive but what was the intent
here? Should the local name variables increase their length or should
the buffer length be reduced?

Cheers,
Nathan