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Date:   Wed, 23 Oct 2019 20:59:52 +0200
From:   Daniel Vetter <daniel@ffwll.ch>
To:     Navid Emamdoost <navid.emamdoost@gmail.com>,
        Navid Emamdoost <emamd001@umn.edu>, Kangjie Lu <kjlu@umn.edu>,
        Stephen McCamant <smccaman@umn.edu>,
        Eric Anholt <eric@anholt.net>, David Airlie <airlied@linux.ie>,
        dri-devel@lists.freedesktop.org,
        LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] drm/v3d: Fix memory leak in v3d_submit_cl_ioctl
Message-ID: <20191023185952.GZ11828@phenom.ffwll.local>
Mail-Followup-To: Navid Emamdoost <navid.emamdoost@gmail.com>,
        Navid Emamdoost <emamd001@umn.edu>, Kangjie Lu <kjlu@umn.edu>,
        Stephen McCamant <smccaman@umn.edu>, Eric Anholt <eric@anholt.net>,
        David Airlie <airlied@linux.ie>, dri-devel@lists.freedesktop.org,
        LKML <linux-kernel@vger.kernel.org>
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On Wed, Oct 23, 2019 at 11:16:01AM +0200, Daniel Vetter wrote:
> On Tue, Oct 22, 2019 at 10:53:57PM -0500, Navid Emamdoost wrote:
> > On Tue, Oct 22, 2019 at 4:36 AM Daniel Vetter <daniel@ffwll.ch> wrote:
> > >
> > > On Mon, Oct 21, 2019 at 01:52:49PM -0500, Navid Emamdoost wrote:
> > > > In the impelementation of v3d_submit_cl_ioctl() there are two memory
> > > > leaks. One is when allocation for bin fails, and the other is when bin
> > > > initialization fails. If kcalloc fails to allocate memory for bin then
> > > > render->base should be put. Also, if v3d_job_init() fails to initialize
> > > > bin->base then allocated memory for bin should be released.
> > > >
> > > > Fixes: a783a09ee76d ("drm/v3d: Refactor job management.")
> > > > Signed-off-by: Navid Emamdoost <navid.emamdoost@gmail.com>
> > > > ---
> > > >  drivers/gpu/drm/v3d/v3d_gem.c | 5 ++++-
> > > >  1 file changed, 4 insertions(+), 1 deletion(-)
> > > >
> > > > diff --git a/drivers/gpu/drm/v3d/v3d_gem.c b/drivers/gpu/drm/v3d/v3d_gem.c
> > > > index 5d80507b539b..19c092d75266 100644
> > > > --- a/drivers/gpu/drm/v3d/v3d_gem.c
> > > > +++ b/drivers/gpu/drm/v3d/v3d_gem.c
> > > > @@ -557,13 +557,16 @@ v3d_submit_cl_ioctl(struct drm_device *dev, void *data,
> > > >
> > > >       if (args->bcl_start != args->bcl_end) {
> > > >               bin = kcalloc(1, sizeof(*bin), GFP_KERNEL);
> > > > -             if (!bin)
> > > > +             if (!bin) {
> > > > +                     v3d_job_put(&render->base);
> > >
> > > The job isn't initialized yet, this doesn't work.
> > Do you mean we have to release render via kfree() here?
> > 
> > >
> > > >                       return -ENOMEM;
> > > > +             }
> > > >
> > > >               ret = v3d_job_init(v3d, file_priv, &bin->base,
> > > >                                  v3d_job_free, args->in_sync_bcl);
> > > >               if (ret) {
> > > >                       v3d_job_put(&render->base);
> > >
> > > v3d_job_put will call kfree, if you chase the callchain long enough (in
> > > v3d_job_free). So no bug here, this would lead to a double kfree and
> > > crash.
> > Yes, v3d_job_put() takes care of render,
> > 
> > > -Daniel
> > >
> > > > +                     kfree(bin);
> > but how about leaking bin?
> 
> Sorry, I totally missed that this is bin, no render. Patch looks correct
> to me.
> 
> Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>

Double-checked with Eric and applied to drm-misc-fixes.
-Daniel

> 
> > 
> > > >                       return ret;
> > > >               }
> > > >
> > > > --
> > > > 2.17.1
> > > >
> > >
> > > --
> > > Daniel Vetter
> > > Software Engineer, Intel Corporation
> > > http://blog.ffwll.ch
> > 
> > 
> > 
> > -- 
> > Navid.
> 
> -- 
> Daniel Vetter
> Software Engineer, Intel Corporation
> http://blog.ffwll.ch

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch