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Date:   Wed, 15 Sep 2021 15:44:41 +0000
From:   Anel Orazgaliyeva <anelkz@...zon.de>
To:     "Rafael J. Wysocki" <rafael@...nel.org>
CC:     Aman Priyadarshi <apeureka@...zon.de>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        <linux-pm@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] cpuidle: Fix memory leaks

> On Wed, Sep 15, 2021 at 02:14:56PM +0200, Rafael J. Wysocki wrote:
> CAUTION: This email originated from outside of the organization. Do not click links or open attachments unless you can confirm the sender and know the content is safe.
> 
> 
> 
> On Mon, Sep 6, 2021 at 8:35 PM Anel Orazgaliyeva <anelkz@...zon.de> wrote:
> >
> > Commit c343bf1ba5ef ("cpuidle: Fix three reference count leaks")
> > fixes the cleanup of kobjects; however, it removes kfree() calls
> > altogether, leading to memory leaks.
> 
> Wait, won't the cleanup be done by cpuidle_free_state_kobj()?

For state cleanup, cpuidle_free_state_kobj() is called on the all the previously created kobjs:

error_state:
        for (i = i - 1; i >= 0; i--)
                cpuidle_free_state_kobj(device, i);

so we still need to cleanup the kobj created in the current iteration.


For overall sysfs, the flow is as follows:

cpuidle_register_device
     ret = cpuidle_add_sysfs(dev);
    if (ret)
        goto out_unregister;

out_unregister:
    __cpuidle_unregister_device(dev);
   goto out_unlock;

so when there is an error in cpuidle_add_sysfs() dev doesn’t get freed.

> 
> > Fix those and also defer the initialization of dev->kobj_dev until
> > after the error check, so that we do not end up with a dangling
> > pointer.
> >
> > Signed-off-by: Anel Orazgaliyeva <anelkz@...zon.de>
> > Suggested-by: Aman Priyadarshi <apeureka@...zon.de>
> > ---
> >  drivers/cpuidle/sysfs.c | 5 ++++-
> >  1 file changed, 4 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/cpuidle/sysfs.c b/drivers/cpuidle/sysfs.c
> > index 53ec9585ccd4..469e18547d06 100644
> > --- a/drivers/cpuidle/sysfs.c
> > +++ b/drivers/cpuidle/sysfs.c
> > @@ -488,6 +488,7 @@ static int cpuidle_add_state_sysfs(struct cpuidle_device *device)
> >                                            &kdev->kobj, "state%d", i);
> >                 if (ret) {
> >                         kobject_put(&kobj->kobj);
> > +                       kfree(kobj);
> >                         goto error_state;
> >                 }
> >                 cpuidle_add_s2idle_attr_group(kobj);
> > @@ -619,6 +620,7 @@ static int cpuidle_add_driver_sysfs(struct cpuidle_device *dev)
> >                                    &kdev->kobj, "driver");
> >         if (ret) {
> >                 kobject_put(&kdrv->kobj);
> > +               kfree(kdrv);
> >                 return ret;
> >         }
> >
> > @@ -705,7 +707,6 @@ int cpuidle_add_sysfs(struct cpuidle_device *dev)
> >         if (!kdev)
> >                 return -ENOMEM;
> >         kdev->dev = dev;
> > -       dev->kobj_dev = kdev;
> >
> >         init_completion(&kdev->kobj_unregister);
> >
> > @@ -713,9 +714,11 @@ int cpuidle_add_sysfs(struct cpuidle_device *dev)
> >                                    "cpuidle");
> >         if (error) {
> >                 kobject_put(&kdev->kobj);
> > +               kfree(kdev);
> >                 return error;
> >         }
> >
> > +       dev->kobj_dev = kdev;
> >         kobject_uevent(&kdev->kobj, KOBJ_ADD);
> >
> >         return 0;
> > --
> > 2.32.0
> >
> >
> >
> >
> > Amazon Development Center Germany GmbH
> > Krausenstr. 38
> > 10117 Berlin
> > Geschaeftsfuehrung: Christian Schlaeger, Jonathan Weiss
> > Eingetragen am Amtsgericht Charlottenburg unter HRB 149173 B
> > Sitz: Berlin
> > Ust-ID: DE 289 237 879

On Wed, Sep 15, 2021 at 02:14:56PM +0200, Rafael J. Wysocki wrote:
> CAUTION: This email originated from outside of the organization. Do not click links or open attachments unless you can confirm the sender and know the content is safe.
> 
> 
> 
> On Mon, Sep 6, 2021 at 8:35 PM Anel Orazgaliyeva <anelkz@...zon.de> wrote:
> >
> > Commit c343bf1ba5ef ("cpuidle: Fix three reference count leaks")
> > fixes the cleanup of kobjects; however, it removes kfree() calls
> > altogether, leading to memory leaks.
> 
> Wait, won't the cleanup be done by cpuidle_free_state_kobj()?
> 
> > Fix those and also defer the initialization of dev->kobj_dev until
> > after the error check, so that we do not end up with a dangling
> > pointer.
> >
> > Signed-off-by: Anel Orazgaliyeva <anelkz@...zon.de>
> > Suggested-by: Aman Priyadarshi <apeureka@...zon.de>
> > ---
> >  drivers/cpuidle/sysfs.c | 5 ++++-
> >  1 file changed, 4 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/cpuidle/sysfs.c b/drivers/cpuidle/sysfs.c
> > index 53ec9585ccd4..469e18547d06 100644
> > --- a/drivers/cpuidle/sysfs.c
> > +++ b/drivers/cpuidle/sysfs.c
> > @@ -488,6 +488,7 @@ static int cpuidle_add_state_sysfs(struct cpuidle_device *device)
> >                                            &kdev->kobj, "state%d", i);
> >                 if (ret) {
> >                         kobject_put(&kobj->kobj);
> > +                       kfree(kobj);
> >                         goto error_state;
> >                 }
> >                 cpuidle_add_s2idle_attr_group(kobj);
> > @@ -619,6 +620,7 @@ static int cpuidle_add_driver_sysfs(struct cpuidle_device *dev)
> >                                    &kdev->kobj, "driver");
> >         if (ret) {
> >                 kobject_put(&kdrv->kobj);
> > +               kfree(kdrv);
> >                 return ret;
> >         }
> >
> > @@ -705,7 +707,6 @@ int cpuidle_add_sysfs(struct cpuidle_device *dev)
> >         if (!kdev)
> >                 return -ENOMEM;
> >         kdev->dev = dev;
> > -       dev->kobj_dev = kdev;
> >
> >         init_completion(&kdev->kobj_unregister);
> >
> > @@ -713,9 +714,11 @@ int cpuidle_add_sysfs(struct cpuidle_device *dev)
> >                                    "cpuidle");
> >         if (error) {
> >                 kobject_put(&kdev->kobj);
> > +               kfree(kdev);
> >                 return error;
> >         }
> >
> > +       dev->kobj_dev = kdev;
> >         kobject_uevent(&kdev->kobj, KOBJ_ADD);
> >
> >         return 0;
> > --
> > 2.32.0
> >
> >
> >
> >
> > Amazon Development Center Germany GmbH
> > Krausenstr. 38
> > 10117 Berlin
> > Geschaeftsfuehrung: Christian Schlaeger, Jonathan Weiss
> > Eingetragen am Amtsgericht Charlottenburg unter HRB 149173 B
> > Sitz: Berlin
> > Ust-ID: DE 289 237 879
> >
> >
> >



Amazon Development Center Germany GmbH
Krausenstr. 38
10117 Berlin
Geschaeftsfuehrung: Christian Schlaeger, Jonathan Weiss
Eingetragen am Amtsgericht Charlottenburg unter HRB 149173 B
Sitz: Berlin
Ust-ID: DE 289 237 879


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