[Mesa-dev] [Mesa-stable] [PATCH v2 4/4] dri/common: clear the loaderPrivate pointer in driDestroyDrawable

[Marek Olšák]

Rb for the series. Posting from phone.

Marek

On Feb 2, 2017 6:20 PM, "Nicolai Hähnle" <nhaehnle at gmail.com> wrote:

> From: Nicolai Hähnle <nicolai.haehnle at amd.com>
>
> The GLX specification says about glXDestroyPixmap:
>
>     "The storage for the GLX pixmap will be freed when it is not current
>      to any client."
>
> We're not really following this language to the letter: some of the storage
> is freed immediately (in particular, the dri3_drawable, which contains both
> GLXDRIdrawable and loader_dri3_drawable). So we NULL out the pointers to
> that freed storage; the previous patches added the corresponding
> NULL-pointer
> checks.
>
> This fixes memory corruption in piglit
> ./bin/glx-visuals-depth/stencil -pixmap -auto
>
> Cc: 17.0 <mesa-stable at lists.freedesktop.org>
> Reviewed-by: Marek Olšák <marek.olsak at amd.com>
> ---
>  src/mesa/drivers/dri/common/dri_util.c | 12 ++++++++++++
>  1 file changed, 12 insertions(+)
>
> diff --git a/src/mesa/drivers/dri/common/dri_util.c
> b/src/mesa/drivers/dri/common/dri_util.c
> index f92eee9..d18c458 100644
> --- a/src/mesa/drivers/dri/common/dri_util.c
> +++ b/src/mesa/drivers/dri/common/dri_util.c
> @@ -638,20 +638,22 @@ static void dri_put_drawable(__DRIdrawable *pdp)
>      }
>  }
>
>  static __DRIdrawable *
>  driCreateNewDrawable(__DRIscreen *screen,
>                       const __DRIconfig *config,
>                       void *data)
>  {
>      __DRIdrawable *pdraw;
>
> +    assert(data != NULL);
> +
>      pdraw = malloc(sizeof *pdraw);
>      if (!pdraw)
>         return NULL;
>
>      pdraw->loaderPrivate = data;
>
>      pdraw->driScreenPriv = screen;
>      pdraw->driContextPriv = NULL;
>      pdraw->refcount = 0;
>      pdraw->lastStamp = 0;
> @@ -667,20 +669,30 @@ driCreateNewDrawable(__DRIscreen *screen,
>      }
>
>      pdraw->dri2.stamp = pdraw->lastStamp + 1;
>
>      return pdraw;
>  }
>
>  static void
>  driDestroyDrawable(__DRIdrawable *pdp)
>  {
> +    /*
> +     * The loader's data structures are going away, even if pdp itself
> stays
> +     * around for the time being because it is currently bound. This
> happens
> +     * when a currently bound GLX pixmap is destroyed.
> +     *
> +     * Clear out the pointer back into the loader's data structures to
> avoid
> +     * accessing an outdated pointer.
> +     */
> +    pdp->loaderPrivate = NULL;
> +
>      dri_put_drawable(pdp);
>  }
>
>  static __DRIbuffer *
>  dri2AllocateBuffer(__DRIscreen *screen,
>                    unsigned int attachment, unsigned int format,
>                    int width, int height)
>  {
>      return screen->driver->AllocateBuffer(screen, attachment, format,
>                                            width, height);
> --
> 2.9.3
>
> _______________________________________________
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> mesa-stable at lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/mesa-stable
>
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