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References: <20230603074345.17907-1-lm0963hack@gmail.com> <e337dec6-0b0e-7e53-e38d-ae1791b98418@amd.com>
In-Reply-To: <e337dec6-0b0e-7e53-e38d-ae1791b98418@amd.com>
From:   Alex Deucher <alexdeucher@gmail.com>
Date:   Mon, 5 Jun 2023 11:21:58 -0400
Message-ID: <CADnq5_N=enSchma5R7d8q9t8SkJ_Z7oFxDFHp3a+ypqenO=DYA@mail.gmail.com>
Subject: Re: [PATCH v2] drm/radeon: fix race condition UAF in radeon_gem_set_domain_ioctl
To:     =?UTF-8?Q?Christian_K=C3=B6nig?= <christian.koenig@amd.com>
Cc:     Min Li <lm0963hack@gmail.com>, alexander.deucher@amd.com,
        Xinhui.Pan@amd.com, linux-kernel@vger.kernel.org,
        amd-gfx@lists.freedesktop.org, linaro-mm-sig@lists.linaro.org,
        dri-devel@lists.freedesktop.org, sumit.semwal@linaro.org,
        linux-media@vger.kernel.org
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Applied.  Thanks!

On Mon, Jun 5, 2023 at 4:13=E2=80=AFAM Christian K=C3=B6nig <christian.koen=
ig@amd.com> wrote:
>
> Am 03.06.23 um 09:43 schrieb Min Li:
> > Userspace can race to free the gobj(robj converted from), robj should n=
ot
> > be accessed again after drm_gem_object_put, otherwith it will result in
> > use-after-free.
> >
> > Signed-off-by: Min Li <lm0963hack@gmail.com>
>
> Reviewed-by: Christian K=C3=B6nig <christian.koenig@amd.com>
>
> > ---
> > Changes in v2:
> > - Remove unused robj, avoid compile complain
> >
> >   drivers/gpu/drm/radeon/radeon_gem.c | 4 +---
> >   1 file changed, 1 insertion(+), 3 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/radeon/radeon_gem.c b/drivers/gpu/drm/rade=
on/radeon_gem.c
> > index bdc5af23f005..d3f5ddbc1704 100644
> > --- a/drivers/gpu/drm/radeon/radeon_gem.c
> > +++ b/drivers/gpu/drm/radeon/radeon_gem.c
> > @@ -459,7 +459,6 @@ int radeon_gem_set_domain_ioctl(struct drm_device *=
dev, void *data,
> >       struct radeon_device *rdev =3D dev->dev_private;
> >       struct drm_radeon_gem_set_domain *args =3D data;
> >       struct drm_gem_object *gobj;
> > -     struct radeon_bo *robj;
> >       int r;
> >
> >       /* for now if someone requests domain CPU -
> > @@ -472,13 +471,12 @@ int radeon_gem_set_domain_ioctl(struct drm_device=
 *dev, void *data,
> >               up_read(&rdev->exclusive_lock);
> >               return -ENOENT;
> >       }
> > -     robj =3D gem_to_radeon_bo(gobj);
> >
> >       r =3D radeon_gem_set_domain(gobj, args->read_domains, args->write=
_domain);
> >
> >       drm_gem_object_put(gobj);
> >       up_read(&rdev->exclusive_lock);
> > -     r =3D radeon_gem_handle_lockup(robj->rdev, r);
> > +     r =3D radeon_gem_handle_lockup(rdev, r);
> >       return r;
> >   }
> >
>