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

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Date:   Tue, 20 Aug 2019 23:31:20 -0400
From:   Wenwen Wang <wenwen@...uga.edu>
To:     Bjorn Helgaas <helgaas@...nel.org>
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>,
        Wenwen Wang <wenwen@...uga.edu>
Subject: Re: [PATCH] ACPI / PCI: fix a memory leak bug

On Mon, Aug 19, 2019 at 5:23 PM Bjorn Helgaas <helgaas@...nel.org> wrote:
>
> 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
> >

Thanks for your comments and suggestions! I will rework the patch.

Wenwen