linux-kernel - Re: [PATCH v1] drivers/acpi/processor_idle: check the return value of acpi_fetch_acpi

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Message-ID: <CAMEuxRryb0L6O92r-qzJ8VaBEpW+cghhoZFi6+RtFfDtDWD3sA@mail.gmail.com>
Date:   Sat, 3 Sep 2022 16:03:50 -0700
From:   Li Zhong <floridsleeves@...il.com>
To:     "Rafael J. Wysocki" <rafael@...nel.org>
Cc:     Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
        Len Brown <lenb@...nel.org>
Subject: Re: [PATCH v1] drivers/acpi/processor_idle: check the return value of acpi_fetch_acpi_dev()

On Mon, Aug 29, 2022 at 6:56 AM Rafael J. Wysocki <rafael@...nel.org> wrote:
>
> On Sun, Aug 28, 2022 at 10:54 PM Li Zhong <floridsleeves@...il.com> wrote:
> >
> > The return value of acpi_fetch_acpi_dev() could be NULL, which will
> > cause null pointer dereference if used in acpi_device_hid().
>
> That's true.
>
> > Signed-off-by: Li Zhong <floridsleeves@...il.com>
> > ---
> >  drivers/acpi/processor_idle.c | 2 ++
> >  1 file changed, 2 insertions(+)
> >
> > diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.c
> > index 16a1663d02d4..519f8f741da3 100644
> > --- a/drivers/acpi/processor_idle.c
> > +++ b/drivers/acpi/processor_idle.c
> > @@ -1117,6 +1117,8 @@ static int acpi_processor_get_lpi_info(struct acpi_processor *pr)
> >         status = acpi_get_parent(handle, &pr_ahandle);
> >         while (ACPI_SUCCESS(status)) {
> >                 d = acpi_fetch_acpi_dev(pr_ahandle);
> > +               if (!d)
> > +                       break;
>
> But shouldn't this be continue?
>

I think here is break instead of continue because if we use continue, variable
status will not change. Then the while condition will stay true and loop
forever.

> >                 handle = pr_ahandle;
> >
> >                 if (strcmp(acpi_device_hid(d), ACPI_PROCESSOR_CONTAINER_HID))
> > --
> > 2.25.1
> >