[Mesa-dev] [PATCH] xlib: fix memory leak on Display close

[John Sheu]

On Tue, Apr 12, 2016 at 11:53 AM, John Sheu <sheu at google.com> wrote:
> The XMesaVisual instances freed in the visuals table on display close
> are being freed with a free() call, instead of XMesaDestroyVisual(),
> causing a memory leak.
>
> Signed-off-by: John Sheu <sheu at google.com>
> ---
>  src/mesa/drivers/x11/fakeglx.c | 2 +-
>  src/mesa/drivers/x11/xm_api.c  | 1 +
>  2 files changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/src/mesa/drivers/x11/fakeglx.c b/src/mesa/drivers/x11/fakeglx.c
> index 80b71765..2f4d9669 100644
> --- a/src/mesa/drivers/x11/fakeglx.c
> +++ b/src/mesa/drivers/x11/fakeglx.c
> @@ -794,7 +794,7 @@ destroy_visuals_on_display(Display *dpy)
>        if (VisualTable[i]->display == dpy) {
>           /* remove this visual */
>           int j;
> -         free(VisualTable[i]);
> +         XMesaDestroyVisual(VisualTable[i]);
>           for (j = i; j < NumVisuals - 1; j++)
>              VisualTable[j] = VisualTable[j + 1];
>           NumVisuals--;
> diff --git a/src/mesa/drivers/x11/xm_api.c b/src/mesa/drivers/x11/xm_api.c
> index 65e7ca89..82c4d188 100644
> --- a/src/mesa/drivers/x11/xm_api.c
> +++ b/src/mesa/drivers/x11/xm_api.c
> @@ -856,6 +856,7 @@ XMesaVisual XMesaCreateVisual( XMesaDisplay *display,
>                                  accum_red_size, accum_green_size,
>                                  accum_blue_size, accum_alpha_size,
>                                  0)) {
> +      free(v->visinfo);
>        free(v);
>        return NULL;
>     }
> --
> 2.8.0.rc3.226.g39d4020
>

Thanks!  The implementations in xm_api.c are mostly good, with the exception
of the one place I fixed.  Since XMesaDestroyVisual is a
"client-facing" call, I opted
to manually fix the free() to preserve layering.

As to how it was found, well, automated unittesting + automated heapchecker :-)

-John Sheu