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LibGfx: Make Font atomically ref-counted

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Font objects are cached per-Typeface with non-atomic RefCounted, but
GlyphRun (which is AtomicRefCounted) holds a NonnullRefPtr<Font const>
and can be destroyed on the rendering thread when tearing down display
lists. This created a data race on the Font refcount, leading to
use-after-free crashes in Typeface::font() where the cache's
NonnullRefPtr would point to memory already freed by a concurrent
unref.
This commit is contained in:
Andreas Kling 2026-03-13 21:04:12 -05:00 committed by Andreas Kling
parent 19627bba54
commit f146294b23
1 changed files with 2 additions and 1 deletions
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3
Libraries/LibGfx/Font/Font.h
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@ -9,6 +9,7 @@
#pragma once
#include <AK/AtomicRefCounted.h>
#include <AK/FlyString.h>
#include <AK/RefPtr.h>
#include <AK/Utf16String.h>
@ -54,7 +55,7 @@ enum FontWidth {
constexpr float text_shaping_resolution = 64;
class Font : public RefCounted<Font> {
class Font : public AtomicRefCounted<Font> {
public:
Font(NonnullRefPtr<Typeface const>, float point_width, float point_height, unsigned dpi_x, unsigned dpi_y, FontVariationSettings const variations, ShapeFeatures const& features);
ScaledFontMetrics metrics() const;