linux-kernel - Re: [PATCH] ACPI / PCI: fix a memory leak bug

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Date:   Mon, 19 Aug 2019 16:23:17 -0500
From:   Bjorn Helgaas <helgaas@...nel.org>
To:     Wenwen Wang <wenwen@...uga.edu>
Cc:     "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Len Brown <lenb@...nel.org>,
        "open list:PCI SUBSYSTEM" <linux-pci@...r.kernel.org>,
        "open list:ACPI" <linux-acpi@...r.kernel.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] ACPI / PCI: fix a memory leak bug

The subject line should give a clue about where the leak is, e.g.,

  ACPI / PCI: fix acpi_pci_irq_enable() memory leak

On Thu, Aug 15, 2019 at 11:33:22PM -0500, Wenwen Wang wrote:
> In acpi_pci_irq_enable(), 'entry' is allocated by invoking
> acpi_pci_irq_lookup(). However, it is not deallocated if
> acpi_pci_irq_valid() returns false, leading to a memory leak. To fix this
> issue, free 'entry' before returning 0.

I think the corresponding kzalloc() is the one in
acpi_pci_irq_check_entry().

> Signed-off-by: Wenwen Wang <wenwen@...uga.edu>
> ---
>  drivers/acpi/pci_irq.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/acpi/pci_irq.c b/drivers/acpi/pci_irq.c
> index d2549ae..dea8a60 100644
> --- a/drivers/acpi/pci_irq.c
> +++ b/drivers/acpi/pci_irq.c
> @@ -449,8 +449,10 @@ int acpi_pci_irq_enable(struct pci_dev *dev)
>  		 * No IRQ known to the ACPI subsystem - maybe the BIOS /
>  		 * driver reported one, then use it. Exit in any case.
>  		 */
> -		if (!acpi_pci_irq_valid(dev, pin))
> +		if (!acpi_pci_irq_valid(dev, pin)) {
> +			kfree(entry);
>  			return 0;
> +		}

Looks like we missed this when e237a5518425 ("x86/ACPI/PCI: Recognize
that Interrupt Line 255 means "not connected"") was merged.

You could add:

Fixes: e237a5518425 ("x86/ACPI/PCI: Recognize that Interrupt Line 255 means "not connected"")

>  		if (acpi_isa_register_gsi(dev))
>  			dev_warn(&dev->dev, "PCI INT %c: no GSI\n",
> -- 
> 2.7.4
>