[Mesa-dev] [PATCH] egl/android: fix segfault within swap_buffers

[Emil Velikov]

On 18 May 2017 at 08:21, Tapani Pälli <tapani.palli at intel.com> wrote:
> Function droid_swap_buffers may get called without dri2_surf->buffer set,
> in these cases we don't have a back buffer set either. Patch fixes segfault
> seen with 3DMark that uses android.opengl.GLSurfaceView for rendering it's UI.
>
> backtrace:
>    #00 pc 00013f88  /system/lib/egl/libGLES_mesa.so (droid_swap_buffers+104)
>    #01 pc 000117b2  /system/lib/egl/libGLES_mesa.so (dri2_swap_buffers+50)
>    #02 pc 000058b2  /system/lib/egl/libGLES_mesa.so (eglSwapBuffers+386)
>    #03 pc 00011329  /system/lib/libEGL.so (eglSwapBuffersWithDamageKHR+553)
>    #04 pc 000118e7  /system/lib/libEGL.so (eglSwapBuffers+55)
>    #05 pc 000754dc  /system/lib/libandroid_runtime.so
>
> Note, this is v1 as v2 caused dEQP regressions.
>
> Fixes: 2acc69d ("EGL/Android: Add EGL_EXT_buffer_age extension")
> Signed-off-by: Tapani Pälli <tapani.palli at intel.com>
> ---
>  src/egl/drivers/dri2/platform_android.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/src/egl/drivers/dri2/platform_android.c b/src/egl/drivers/dri2/platform_android.c
> index 49cbeb4..88f6af8 100644
> --- a/src/egl/drivers/dri2/platform_android.c
> +++ b/src/egl/drivers/dri2/platform_android.c
> @@ -628,7 +628,9 @@ droid_swap_buffers(_EGLDriver *drv, _EGLDisplay *disp, _EGLSurface *draw)
>        if (dri2_surf->color_buffers[i].age > 0)
>           dri2_surf->color_buffers[i].age++;
>     }
> -   dri2_surf->back->age = 1;
> +
> +   if (dri2_surf->back)
> +      dri2_surf->back->age = 1;

Doesn't seem quite right to use get_back_bo() elsewhere and a NULL check here.

With a inline comment vaguely like "XXX: we don't use get_back_bo()
since it causes regressions in $app/test."
Acked-by: Emil Velikov <emil.velikov at collabora.com>

-Emil