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st: Guard against spec being invalided during shadow creation

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If an actor is pending a relaying when get_allocation_box() is called,
the method forces an allocation update. In case of StWidget, this might
then result in a style update and a consecutive invalidation of the
shadow spec - we will then try to create a shadow specified by random
memory, with undefined (though likely fatal) consequences.

Guard against this by taking a temporary reference during the function
call.

https://bugzilla.gnome.org/show_bug.cgi?id=788908
This commit is contained in:
Florian Müllner 2018-02-20 17:23:16 +01:00
parent a347ed9912
commit 9d133d8ebb
1 changed files with 11 additions and 3 deletions
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14
src/st/st-private.c
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@ -417,11 +417,17 @@ _st_create_shadow_pipeline_from_actor (StShadow *shadow_spec,
ClutterActorBox box; ClutterActorBox box;
float width, height; float width, height;
/* Querying the actor's allocation may force an allocation update, which
* may cause a style update, which then may invalidate shadow_spec; make
* sure the spec is kept alive by taking a temporary reference
*/
st_shadow_spec_ref (shadow_spec);
clutter_actor_get_allocation_box (actor, &box); clutter_actor_get_allocation_box (actor, &box);
clutter_actor_box_get_size (&box, &width, &height); clutter_actor_box_get_size (&box, &width, &height);
if (width == 0 || height == 0) if (width == 0 || height == 0)
return NULL; goto out;
if (CLUTTER_IS_TEXTURE (actor)) if (CLUTTER_IS_TEXTURE (actor))
{ {
@ -448,7 +454,7 @@ _st_create_shadow_pipeline_from_actor (StShadow *shadow_spec,
COGL_PIXEL_FORMAT_ANY); COGL_PIXEL_FORMAT_ANY);
if (buffer == NULL) if (buffer == NULL)
return NULL; goto out;
offscreen = cogl_offscreen_new_with_texture (buffer); offscreen = cogl_offscreen_new_with_texture (buffer);
fb = COGL_FRAMEBUFFER (offscreen); fb = COGL_FRAMEBUFFER (offscreen);
@ -458,7 +464,7 @@ _st_create_shadow_pipeline_from_actor (StShadow *shadow_spec,
cogl_error_free (catch_error); cogl_error_free (catch_error);
cogl_object_unref (offscreen); cogl_object_unref (offscreen);
cogl_object_unref (buffer); cogl_object_unref (buffer);
return NULL; goto out;
} }
cogl_color_init_from_4ub (&clear_color, 0, 0, 0, 0); cogl_color_init_from_4ub (&clear_color, 0, 0, 0, 0);
@ -488,6 +494,8 @@ _st_create_shadow_pipeline_from_actor (StShadow *shadow_spec,
cogl_object_unref (buffer); cogl_object_unref (buffer);
} }
st_shadow_spec_unref (shadow_spec);
return shadow_pipeline; return shadow_pipeline;
} }