[PATCH 3/3] pm: domains: avoid potential oops in pm_genpd_remove_device()

[Ulf Hansson]

On 20 March 2015 at 18:20, Russell King <rmk+kernel at arm.linux.org.uk> wrote:
> pm_genpd_remove_device() tries hard to validate the generic PM domain
> passed to it, but the validation is not complete.
>
> dev->pm_domain contains a struct dev_pm_domain, which is the "base
> class" of generic PM domains.  Other users of dev_pm_domains include
> stuff like vga_switheroo.  Hence, a device could have a generic PM
> domain or a vga_switcheroo PM domain in dev->pm_domain.
>
> We need ot be certain that the PM domain is actually valid before we
> try to remove it.  We can do this easily as we have a way to get the
> current validated generic PM domain for a struct device.  This must
> match the generic PM domain being requested for removal.
>
> Convert the code to use this alternative validation method instead.
>
> Acked-by: Kevin Hilman <khilman at linaro.org>
> Signed-off-by: Russell King <rmk+kernel at arm.linux.org.uk>

Acked-by: Ulf Hansson <ulf.hansson at linaro.org>

> ---
>  drivers/base/power/domain.c | 4 +---
>  1 file changed, 1 insertion(+), 3 deletions(-)
>
> diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c
> index 89d2eea7f561..5f560fa45a32 100644
> --- a/drivers/base/power/domain.c
> +++ b/drivers/base/power/domain.c
> @@ -1538,9 +1538,7 @@ int pm_genpd_remove_device(struct generic_pm_domain *genpd,
>
>         dev_dbg(dev, "%s()\n", __func__);
>
> -       if (IS_ERR_OR_NULL(genpd) || IS_ERR_OR_NULL(dev)
> -           ||  IS_ERR_OR_NULL(dev->pm_domain)
> -           ||  pd_to_genpd(dev->pm_domain) != genpd)
> +       if (!genpd || genpd != pm_genpd_lookup_dev(dev))
>                 return -EINVAL;
>
>         genpd_acquire_lock(genpd);
> --
> 1.8.3.1
>