Re: [PATCH] drm/etnaviv: fix reference leak when mmaping imported buffer

From: Christian Gmeiner <christian.gmeiner@gmail.com>
To: Lucas Stach <l.stach@pengutronix.de>
Cc: kernel@pengutronix.de, patchwork-lst@pengutronix.de,
	etnaviv@lists.freedesktop.org, dri-devel@lists.freedesktop.org,
	Russell King <linux+etnaviv@armlinux.org.uk>
Subject: Re: [PATCH] drm/etnaviv: fix reference leak when mmaping imported buffer
Date: Fri, 3 Mar 2023 21:58:31 +0100	[thread overview]
Message-ID: <CAH9NwWfPr-axoa1iS-khG37qQoknnUMHOu5y6orgMQ_sh5JZfw@mail.gmail.com> (raw)
In-Reply-To: <20230228165552.760988-1-l.stach@pengutronix.de>

>
> drm_gem_prime_mmap() takes a reference on the GEM object, but before that
> drm_gem_mmap_obj() already takes a reference, which will be leaked as only
> one reference is dropped when the mapping is closed. Drop the extra
> reference when dma_buf_mmap() succeeds.
>
> Signed-off-by: Lucas Stach <l.stach@pengutronix.de>

Reviewed-by: Christian Gmeiner <christian.gmeiner@gmail.com>

> ---
>  drivers/gpu/drm/etnaviv/etnaviv_gem_prime.c | 10 +++++++++-
>  1 file changed, 9 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/etnaviv/etnaviv_gem_prime.c b/drivers/gpu/drm/etnaviv/etnaviv_gem_prime.c
> index 7031db145a77..3524b5811682 100644
> --- a/drivers/gpu/drm/etnaviv/etnaviv_gem_prime.c
> +++ b/drivers/gpu/drm/etnaviv/etnaviv_gem_prime.c
> @@ -91,7 +91,15 @@ static void *etnaviv_gem_prime_vmap_impl(struct etnaviv_gem_object *etnaviv_obj)
>  static int etnaviv_gem_prime_mmap_obj(struct etnaviv_gem_object *etnaviv_obj,
>                 struct vm_area_struct *vma)
>  {
> -       return dma_buf_mmap(etnaviv_obj->base.dma_buf, vma, 0);
> +       int ret;
> +
> +       ret = dma_buf_mmap(etnaviv_obj->base.dma_buf, vma, 0);
> +       if (!ret) {
> +               /* Drop the reference acquired by drm_gem_mmap_obj(). */
> +               drm_gem_object_put(&etnaviv_obj->base);
> +       }
> +
> +       return ret;
>  }
>
>  static const struct etnaviv_gem_ops etnaviv_gem_prime_ops = {
> --
> 2.30.2
>


-- 
greets
--
Christian Gmeiner, MSc

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