linux-kernel - Re: [PATCH] media: davinci: vpif_capture: fix memory leak in vpif

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Date:   Tue, 4 Jun 2019 16:33:46 +0800
From:   Yang Xiao <92siuyang@...il.com>
To:     "Lad, Prabhakar" <prabhakar.csengg@...il.com>
Cc:     Mauro Carvalho Chehab <mchehab@...nel.org>,
        linux-media <linux-media@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Hans Verkuil <hverkuil@...all.nl>
Subject: Re: [PATCH] media: davinci: vpif_capture: fix memory leak in vpif_probe()

On Tue, Jun 4, 2019 at 4:15 PM Lad, Prabhakar
<prabhakar.csengg@...il.com> wrote:
>
> Hi Young,
>
> Thanks for the patch.
>
> On Tue, Jun 4, 2019 at 8:49 AM Young Xiao <92siuyang@...il.com> wrote:
> >
> > If vpif_probe() fails on v4l2_device_register() and vpif_probe_complete(),
> > then memory allocated at initialize_vpif() for global vpif_obj.dev[i]
> > become unreleased.
> >
> > The patch adds deallocation of vpif_obj.dev[i] on the error path.
> >
> > Signed-off-by: Young Xiao <92siuyang@...il.com>
> > ---
> >  drivers/media/platform/davinci/vpif_capture.c | 19 ++++++++++++++++---
> >  1 file changed, 16 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/media/platform/davinci/vpif_capture.c b/drivers/media/platform/davinci/vpif_capture.c
> > index b5aacb0..277d500 100644
> > --- a/drivers/media/platform/davinci/vpif_capture.c
> > +++ b/drivers/media/platform/davinci/vpif_capture.c
> > @@ -1385,6 +1385,14 @@ static int initialize_vpif(void)
> >         return err;
> >  }
> >
> > +static void free_vpif_objs(void)
> > +{
> function could be made inline.
>
> > +       int i;
> > +
> > +       for (i = 0; i < VPIF_DISPLAY_MAX_DEVICES; i++)
>
> VPIF_DISPLAY_MAX_DEVICES ? this should be  VPIF_CAPTURE_MAX_DEVICES
>
> > +               kfree(vpif_obj.dev[i]);
> > +}
> > +
> >  static int vpif_async_bound(struct v4l2_async_notifier *notifier,
> >                             struct v4l2_subdev *subdev,
> >                             struct v4l2_async_subdev *asd)
> > @@ -1654,7 +1662,7 @@ static __init int vpif_probe(struct platform_device *pdev)
> >         err = v4l2_device_register(vpif_dev, &vpif_obj.v4l2_dev);
> >         if (err) {
> >                 v4l2_err(vpif_dev->driver, "Error registering v4l2 device\n");
> > -               goto cleanup;
> > +               goto vpif_free;
> >         }
> >
> >         while ((res = platform_get_resource(pdev, IORESOURCE_IRQ, res_idx))) {
> > @@ -1701,7 +1709,10 @@ static __init int vpif_probe(struct platform_device *pdev)
> >                                   "registered sub device %s\n",
> >                                    subdevdata->name);
> >                 }
> > -               vpif_probe_complete();
> > +               err = vpif_probe_complete();
> > +               if (err) {
> > +                       goto probe_subdev_out;
> > +               }
>
> No need for { and } as per kernel coding style.

Sorry, I can not get your point here.
There is no need to check the return value of vpif_probe_complete(), isn't it?
So, we just fix the memory leak in the error path of v4l2_device_register()?

>
> >         } else {
> >                 vpif_obj.notifier.ops = &vpif_async_ops;
> >                 err = v4l2_async_notifier_register(&vpif_obj.v4l2_dev,
> > @@ -1720,6 +1731,8 @@ static __init int vpif_probe(struct platform_device *pdev)
> >         kfree(vpif_obj.sd);
> >  vpif_unregister:
> >         v4l2_device_unregister(&vpif_obj.v4l2_dev);
> > +vpif_free:
> > +       free_vpif_objs();
> >  cleanup:
> >         v4l2_async_notifier_cleanup(&vpif_obj.notifier);
> >
> > @@ -1748,8 +1761,8 @@ static int vpif_remove(struct platform_device *device)
> >                 ch = vpif_obj.dev[i];
> >                 /* Unregister video device */
> >                 video_unregister_device(&ch->video_dev);
> > -               kfree(vpif_obj.dev[i]);
> >         }
> > +       free_vpif_objs();
>
> no need for this change, leave it as it is.
>
> Cheers,
> Prabhakar Lad



-- 
Best regards!

Young
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