Re: [PATCH] fsl/fman: Fix fm_pdev reference leak in fman_port_probe()

[netdev-bot+sashiko]

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- [High] Incomplete fix plus inaccurate commit message in
  fman_port_probe(): the commit claims the of_find_device_by_node()…

Pre-existing issues:
- [High] fman_port_probe()
  (drivers/net/ethernet/freescale/fman/fman_port.c:1864-1873) treats a…

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fsl/fman: Fix fm_pdev reference leak in fman_port_probe()

This adds a put_device(&fm_pdev->dev) on the success path of
fman_port_probe(), so the reference taken by of_find_device_by_node() is
dropped before returning 0.

> diff --git a/drivers/net/ethernet/freescale/fman/fman_port.c b/drivers/net/ethernet/freescale/fman/fman_port.c
> index 1b8fef69114ed..f44a890165127 100644
> --- a/drivers/net/ethernet/freescale/fman/fman_port.c
> +++ b/drivers/net/ethernet/freescale/fman/fman_port.c
> @@ -1868,6 +1868,8 @@ static int fman_port_probe(struct platform_device *of_dev)
>  
>  	dev_set_drvdata(&of_dev->dev, port);
>  
> +	put_device(&fm_pdev->dev);
> +
>  	return 0;
>  
>  put_device:

[Severity: High]
The commit message says the fm_pdev reference "is released on the error
paths, but the successful path returns without dropping it".  Is that
accurate for all error paths in fman_port_probe()?

The __devm_request_region() failure branch jumps to free_port:, which sits
below the put_device: label:

	dev_res = __devm_request_region(port->dev, &res, res.start,
					resource_size(&res), "fman-port");
	if (!dev_res) {
		dev_err(port->dev, "%s: __devm_request_region() failed\n",
			__func__);
		err = -EINVAL;
		goto free_port;
	}
	...
put_device:
	put_device(&fm_pdev->dev);
return_err:
	of_node_put(port_node);
free_port:
	kfree(port);
	return err;

Does that branch still leak the fm_pdev device reference after this patch?

Would a single put_device(&fm_pdev->dev) right after the last use of
fm_pdev/fman cover both returns instead?

	port->dts_params.fman = fman;
	put_device(&fm_pdev->dev);

	of_node_put(port_node);

Note that redirecting free_port: to the existing put_device: label does not
look workable, since return_err: would then run of_node_put(port_node) a
second time after the of_node_put(port_node) already done just before
__devm_request_region().

[Severity: High]
This isn't a bug introduced by this patch, but right above the newly added
put_device() the devm_ioremap() failure is only logged and probe still
returns 0:

	port->dts_params.base_addr = devm_ioremap(port->dev, res.start,
						  resource_size(&res));
	if (!port->dts_params.base_addr)
		dev_err(port->dev, "%s: devm_ioremap() failed\n", __func__);

	dev_set_drvdata(&of_dev->dev, port);

Can this publish a port with a NULL register base?  fman_port_bind() hands
the drvdata to mac_probe() in fman/mac.c, and dpaa_eth_init_tx_port() /
dpaa_eth_init_rx_port() then call fman_port_config(), which derives the
register windows from that base without checking it:

drivers/net/ethernet/freescale/fman/fman_port.c:fman_port_config() {
	void __iomem *base_addr = port->dts_params.base_addr;
	...
	port->bmi_regs = base_addr + BMI_PORT_REGS_OFFSET;
	port->qmi_regs = base_addr + QMI_PORT_REGS_OFFSET;
	port->hwp_regs = base_addr + HWP_PORT_REGS_OFFSET;
	...
		reg = 0x00001013;
		iowrite32be(reg, &port->bmi_regs->tx.fmbm_tfp);
}

With base_addr NULL, does that iowrite32be() for the A005127 errata (rev >=
6, 1G TX) dereference a near-NULL __iomem pointer, followed by the
ioread32be()/iowrite32be() calls in fman_port_init() and
fman_port_enable()?

Should the devm_ioremap() failure set err = -ENOMEM and take the cleanup
path like the other fatal probe errors?

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Sashiko AI review · https://netdev-ai.bots.linux.dev/sashiko/#/patchset/20260917110726.2148318-1-vulab%40iscas.ac.cn