linux-kernel - Re: [PATCH] ACPI: bus: Avoid non-ACPI device objects in walks over children

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Message-ID: <CAJZ5v0iA-9NFWsxrGZFN4ZeQBHDVniTNtw5HKGa+WKAdUZa02g@mail.gmail.com>
Date:   Fri, 22 Apr 2022 18:00:27 +0200
From:   "Rafael J. Wysocki" <rafael@...nel.org>
To:     Mika Westerberg <mika.westerberg@...ux.intel.com>
Cc:     "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Linux ACPI <linux-acpi@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Bjorn Helgaas <helgaas@...nel.org>,
        Linux PM <linux-pm@...r.kernel.org>
Subject: Re: [PATCH] ACPI: bus: Avoid non-ACPI device objects in walks over children

On Fri, Apr 22, 2022 at 5:27 PM Mika Westerberg
<mika.westerberg@...ux.intel.com> wrote:
>
> Hi Rafael,
>
> On Fri, Apr 22, 2022 at 05:13:48PM +0200, Rafael J. Wysocki wrote:
> > From: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> >
> > When walking the children of an ACPI device, take extra care to avoid
> > using to_acpi_device() on the ones that are not ACPI devices, because
> > that may lead to out-of-bounds access and memory corruption.
> >
> > While at it, make the function passed to acpi_dev_for_each_child()
> > take a struct acpi_device pointer argument (instead of a struct device
> > one), so it is more straightforward to use.
> >
> > Fixes: b7dd6298db81 ("ACPI: PM: Introduce acpi_dev_power_up_children_with_adr()")
> > Reported-by: kernel test robot <oliver.sang@...el.com>
> > BugLink: https://lore.kernel.org/lkml/20220420064725.GB16310@xsang-OptiPlex-9020/
> > Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> > ---
> >
> > The commit being fixed is present in linux-next.
> >
> > ---
> >  drivers/acpi/bus.c       |   24 ++++++++++++++++++++++--
> >  drivers/acpi/device_pm.c |    5 +----
> >  include/acpi/acpi_bus.h  |    2 +-
> >  3 files changed, 24 insertions(+), 7 deletions(-)
> >
> > Index: linux-pm/drivers/acpi/bus.c
> > ===================================================================
> > --- linux-pm.orig/drivers/acpi/bus.c
> > +++ linux-pm/drivers/acpi/bus.c
> > @@ -1070,10 +1070,30 @@ int acpi_bus_for_each_dev(int (*fn)(stru
> >  }
> >  EXPORT_SYMBOL_GPL(acpi_bus_for_each_dev);
> >
> > +struct acpi_dev_walk_context {
> > +     int (*fn)(struct acpi_device *, void *);
> > +     void *data;
> > +};
> > +
> > +static int acpi_dev_for_one_check(struct device *dev, void *context)
> > +{
> > +     struct acpi_dev_walk_context *adwc = context;
> > +
> > +     if (dev->bus != &acpi_bus_type)
> > +             return 0;
>
> I wonder if it make sense to add dev_is_acpi() that does the above
> analoguos to dev_is_pci()?

I thought about that, but this is the only place where it would be
needed ATM, so for now this isn't necessary.

> Regardless of that,
>
> Reviewed-by: Mika Westerberg <mika.westerberg@...ux.intel.com>

Thanks!