Re: [PATCH] ata: libata: Do not leave ata_host_stop() registered when activation fails

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 2 potential issue(s) to consider:

New issues:
- [High] Bypassing `->host_stop()` on activation failure via `ata_host_undo_start()` breaks legacy PCI and OF drivers that rely on devres for hardware and resource cleanup, leading to state/memory leaks and interrupt storms.

Pre-existing issues:
- [High] Missing IRQ cleanup in ahci_host_activate_multi_irqs error path leads to active interrupts during hardware teardown.
--

commit 33ab74bb11edbc6ab549b2a41db1917c6750487f
Author: Niklas Cassel <cassel@kernel.org>

ata: libata: Do not leave ata_host_stop() registered when activation fails

ata_host_start() registers ata_host_stop() as a devres action. This patch
adds ata_host_undo_start() to stop the ports and drop the devres action
without calling ->host_stop() when activation helpers fail, returning
resource release responsibility to the caller.

> diff --git a/drivers/ata/libahci.c b/drivers/ata/libahci.c
> index 6d72eb017b498..7ac1fcdd6d0d7 100644
> --- a/drivers/ata/libahci.c
> +++ b/drivers/ata/libahci.c
> @@ -2723,11 +2723,20 @@ static int ahci_host_activate_multi_irqs(struct ata_host *host,
>  				0, pp->irq_desc, host->ports[i]);
>  
>  		if (rc)
> -			return rc;
> +			goto undo_start;
>  		ata_port_desc_misc(host->ports[i], irq);
>  	}
>  
> -	return ata_host_register(host, sht);
> +	rc = ata_host_register(host, sht);
> +	if (rc)
> +		goto undo_start;
> +
> +	return 0;
> +
> +undo_start:
> +	ata_host_undo_start(host);
> +
> +	return rc;

[Severity: High]
This is a pre-existing issue, but by not freeing the successfully requested
IRQs in this error path before returning, can we cause a kernel panic?

If devm_request_irq() fails for one port, or if ata_host_register() fails,
this jumps to undo_start and returns an error without freeing the IRQs.

The caller (ahci_platform_init_host) and platform driver will then disable
clocks and PHYs via ahci_platform_disable_resources(). If a pending interrupt
fires before the generic devres cleanup eventually frees the IRQs, the
interrupt handler (ahci_multi_irqs_intr_hard) will attempt to access unclocked
AHCI registers.

>  }
>  
>  /**
> diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
> index 59e87b987d73e..4c0ee207f4c64 100644
> --- a/drivers/ata/libata-core.c
> +++ b/drivers/ata/libata-core.c
[ ... ]
> +void ata_host_undo_start(struct ata_host *host)
> +{
> +	int i;
> +
> +	if (!(host->flags & ATA_HOST_STARTED))
> +		return;
> +
> +	for (i = 0; i < host->n_ports; i++) {
> +		struct ata_port *ap = host->ports[i];
> +
> +		if (ap->ops->port_stop)
> +			ap->ops->port_stop(ap);
> +	}
> +
> +	/*
> +	 * Drop the action added by ata_host_start() without calling it.
> +	 * It does not exist if neither ->port_stop() nor ->host_stop() is
> +	 * implemented, in which case there is nothing to drop.
> +	 */
> +	devres_destroy(host->dev, ata_host_stop, NULL, NULL);

[Severity: High]
Does bypassing ->host_stop() here break legacy PCI and OF drivers that rely
entirely on the devres action for hardware and resource cleanup?

For instance, sata_qstor enables hardware interrupts in qs_ata_init_one():

	qs_host_init(host, board_idx);
	pci_set_master(pdev);
	return ata_host_activate(host, pdev->irq, qs_intr, IRQF_SHARED,
				 &qs_ata_sht);

If ata_host_activate() fails, the driver relies on qs_host_stop() to disable
interrupts. By skipping ->host_stop(), wouldn't unhandled hardware interrupts
remain enabled, potentially causing an interrupt storm?

Similarly, sata_nv programs ADMA configuration into PCI registers before
calling ata_pci_sff_activate_host() in nv_init_one(). If activation fails,
nv_adma_host_stop() is bypassed. Does this leak the hardware ADMA
configuration state?

Also, in sata_fsl_probe(), the return value of ata_host_activate() is ignored,
leaving the device bound despite activation failure. With ->host_stop()
bypassed, will this cause resources to leak on unbind?

> +
> +	host->flags &= ~ATA_HOST_STARTED;
> +}
> +EXPORT_SYMBOL_GPL(ata_host_undo_start);

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260909185035.3130774-2-cassel@kernel.org?part=1