[Spice-devel] [PATCH 15/18] worker: s/validate_area/surface_update_dest

[Fabiano Fidêncio]

On Mon, Nov 23, 2015 at 7:11 PM, Frediano Ziglio <fziglio at redhat.com> wrote:
>>
>> From: Marc-André Lureau <marcandre.lureau at gmail.com>
>>
>> ---
>>  server/red_worker.c | 35 ++++++++++++++++-------------------
>>  1 file changed, 16 insertions(+), 19 deletions(-)
>>
>> diff --git a/server/red_worker.c b/server/red_worker.c
>> index becd42f..a82a871 100644
>> --- a/server/red_worker.c
>> +++ b/server/red_worker.c
>> @@ -936,26 +936,23 @@ static void image_surface_init(DisplayChannel *display)
>>      display->image_surfaces.ops = &image_surfaces_ops;
>>  }
>>
>> -static void validate_area(DisplayChannel *display, const SpiceRect *area,
>> uint32_t surface_id)
>> +static void surface_update_dest(RedSurface *surface, const SpiceRect *area)
>>  {
>> -    RedSurface *surface;
>> +    SpiceCanvas *canvas = surface->context.canvas;
>> +    int h = area->bottom - area->top;
>> +    int stride = surface->context.stride;
>> +    uint8_t *line_0 = surface->context.line_0;
>>
>> -    surface = &display->surfaces[surface_id];
>> -    if (!surface->context.canvas_draws_on_surface) {
>> -        SpiceCanvas *canvas = surface->context.canvas;
>> -        int h;
>> -        int stride = surface->context.stride;
>> -        uint8_t *line_0 = surface->context.line_0;
>> +    if (surface->context.canvas_draws_on_surface)
>> +        return;
>> +    if (h == 0)
>> +        return;
>>
>> -        if (!(h = area->bottom - area->top)) {
>> -            return;
>> -        }
>> +    spice_return_if_fail(stride < 0);
>>
>> -        spice_assert(stride < 0);
>> -        uint8_t *dest = line_0 + (area->top * stride) + area->left *
>> sizeof(uint32_t);
>> -        dest += (h - 1) * stride;
>> -        canvas->ops->read_bits(canvas, dest, -stride, area);
>> -    }
>> +    uint8_t *dest = line_0 + (area->top * stride) + area->left *
>> sizeof(uint32_t);
>> +    dest += (h - 1) * stride;
>> +    canvas->ops->read_bits(canvas, dest, -stride, area);
>>  }
>>
>>  /*
>> @@ -1037,7 +1034,7 @@ void display_channel_draw_till(DisplayChannel *display,
>> const SpiceRect *area, i
>>          drawable_draw(display, now);
>>          display_channel_drawable_unref(display, now);
>>      } while (now != surface_last);
>> -    validate_area(display, area, surface_id);
>> +    surface_update_dest(surface, area);
>>  }
>>
>>  void display_channel_draw(DisplayChannel *display, const SpiceRect *area,
>>  int surface_id)
>> @@ -1074,7 +1071,7 @@ void display_channel_draw(DisplayChannel *display,
>> const SpiceRect *area, int su
>>      region_destroy(&rgn);
>>
>>      if (!last) {
>> -        validate_area(display, area, surface_id);
>> +        surface_update_dest(surface, area);
>>          return;
>>      }
>>
>> @@ -1090,7 +1087,7 @@ void display_channel_draw(DisplayChannel *display,
>> const SpiceRect *area, int su
>>          drawable_draw(display, now);
>>          display_channel_drawable_unref(display, now);
>>      } while (now != last);
>> -    validate_area(display, area, surface_id);
>> +    surface_update_dest(surface, area);
>>  }
>>
>>  static int red_process_cursor(RedWorker *worker, uint32_t max_pipe_size, int
>>  *ring_is_empty)
>> --
>> 2.4.3
>>
>
> This is an example on how an innocent patch can cause problems... this cause
> a use after free problem!

Btw, I split this patch ...

>
> Frediano
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