On Fri, Jun 29, 2018 at 05:21:22PM +0200, Christophe de Dinechin wrote:
> From: Christophe de Dinechin <dinechin@xxxxxxxxxx>
>
> In some error cases, canvas_get_image may return NULL.
> When this happens, calls like pixman_image_get_width(s)
> will crash. Add additional error paths to deal with
> these cases.
I assume you don't have a reproducer for this, this is just something
you noticed while looking at that code?
>
> Signed-off-by: Christophe de Dinechin <dinechin@xxxxxxxxxx>
> ---
> common/canvas_base.c | 38 +++++++++++++++++++++++++++++++++++---
> 1 file changed, 35 insertions(+), 3 deletions(-)
>
> diff --git a/common/canvas_base.c b/common/canvas_base.c
> index 6bf6e5d..bbaaf96 100644
> --- a/common/canvas_base.c
> +++ b/common/canvas_base.c
> @@ -3072,6 +3072,7 @@ static void canvas_draw_stroke(SpiceCanvas *spice_canvas, SpiceRect *bbox,
> gc.tile = canvas_get_image(canvas,
> stroke->brush.u.pattern.pat,
> FALSE);
> + spice_return_if_fail(gc.tile != NULL);
I'd favour g_return_if_fail(), I'd really like to kill these various
spice_* calls mirroring glib API. And spice_return_if_fail() will
abort() I think.
> }
> gc.tile_offset_x = stroke->brush.u.pattern.pos.x;
> gc.tile_offset_y = stroke->brush.u.pattern.pos.y;
> @@ -3158,6 +3159,10 @@ static void canvas_draw_rop3(SpiceCanvas *spice_canvas, SpiceRect *bbox,
> heigth = bbox->bottom - bbox->top;
>
> d = canvas_get_image_from_self(spice_canvas, bbox->left, bbox->top, width, heigth, FALSE);
> + if (d == NULL) {
> + spice_critical("no rop3 destination");
spice_critical calls abort() too
> + goto d_error;
> + }
> surface_canvas = canvas_get_surface(canvas, rop3->src_bitmap);
> if (surface_canvas) {
> s = surface_canvas->ops->get_image(surface_canvas, FALSE);
> @@ -3176,10 +3181,14 @@ static void canvas_draw_rop3(SpiceCanvas *spice_canvas, SpiceRect *bbox,
> src_pos.x = rop3->src_area.left;
> src_pos.y = rop3->src_area.top;
> }
> + if (s == NULL) {
> + spice_critical("no rop3 source");
> + goto s_error;
> + }
> if (pixman_image_get_width(s) - src_pos.x < width ||
> pixman_image_get_height(s) - src_pos.y < heigth) {
> spice_critical("bad src bitmap size");
> - return;
> + goto s_error;
> }
> if (rop3->brush.type == SPICE_BRUSH_TYPE_PATTERN) {
> SpiceCanvas *_surface_canvas;
> @@ -3191,6 +3200,12 @@ static void canvas_draw_rop3(SpiceCanvas *spice_canvas, SpiceRect *bbox,
> } else {
> p = canvas_get_image(canvas, rop3->brush.u.pattern.pat, FALSE);
> }
> + if (p == NULL) {
> + spice_critical("no rop3 pattern");
> + /* degrade to color only */
> + do_rop3_with_color(rop3->rop3, d, s, &src_pos, rop3->brush.u.color);
Could you test this? If not, I feel a bit uncomfortable adding such a
fallback.
> + goto p_error;
> + }
> SpicePoint pat_pos;
>
> pat_pos.x = (bbox->left - rop3->brush.u.pattern.pos.x) % pixman_image_get_width(p);
> @@ -3200,14 +3215,16 @@ static void canvas_draw_rop3(SpiceCanvas *spice_canvas, SpiceRect *bbox,
> } else {
> do_rop3_with_color(rop3->rop3, d, s, &src_pos, rop3->brush.u.color);
> }
> +p_error:
Do we need 3 labels with very similar names? I'd think something like
this could work?
error:
if (s != NULL) {
pixman_image_unref(s);
spice_canvas->ops->blit_image(spice_canvas, &dest_region, d,
bbox->left,
bbox->top);
}
if (d != NULL) {
pixman_image_unref(d);
}
pixman_region32_fini(&dest_region);
Christophe
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