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imgui_freetype: Assert if bitmap size exceed chunk size to avoid buffer overflow. (#5731)

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cfillion 2022-09-28 23:37:39 -04:00 committed by ocornut
parent f2a522d70d
commit 5884219867
1 changed files with 2 additions and 1 deletions
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3
misc/freetype/imgui_freetype.cpp
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@ -508,7 +508,7 @@ bool ImFontAtlasBuildWithFreeTypeEx(FT_Library ft_library, ImFontAtlas* atlas, u
// Allocate temporary rasterization data buffers. // Allocate temporary rasterization data buffers.
// We could not find a way to retrieve accurate glyph size without rendering them. // We could not find a way to retrieve accurate glyph size without rendering them.
// (e.g. slot->metrics->width not always matching bitmap->width, especially considering the Oblique transform) // (e.g. slot->metrics->width not always matching bitmap->width, especially considering the Oblique transform)
// We allocate in chunks of 256 KB to not waste too much extra memory ahead. Hopefully users of FreeType won't find the temporary allocations. // We allocate in chunks of 256 KB to not waste too much extra memory ahead. Hopefully users of FreeType won't mind the temporary allocations.
const int BITMAP_BUFFERS_CHUNK_SIZE = 256 * 1024; const int BITMAP_BUFFERS_CHUNK_SIZE = 256 * 1024;
int buf_bitmap_current_used_bytes = 0; int buf_bitmap_current_used_bytes = 0;
ImVector<unsigned char*> buf_bitmap_buffers; ImVector<unsigned char*> buf_bitmap_buffers;
@ -556,6 +556,7 @@ bool ImFontAtlasBuildWithFreeTypeEx(FT_Library ft_library, ImFontAtlas* atlas, u
buf_bitmap_current_used_bytes = 0; buf_bitmap_current_used_bytes = 0;
buf_bitmap_buffers.push_back((unsigned char*)IM_ALLOC(BITMAP_BUFFERS_CHUNK_SIZE)); buf_bitmap_buffers.push_back((unsigned char*)IM_ALLOC(BITMAP_BUFFERS_CHUNK_SIZE));
} }
IM_ASSERT(buf_bitmap_current_used_bytes + bitmap_size_in_bytes <= BITMAP_BUFFERS_CHUNK_SIZE); // We could probably allocate custom-sized buffer instead.
// Blit rasterized pixels to our temporary buffer and keep a pointer to it. // Blit rasterized pixels to our temporary buffer and keep a pointer to it.
src_glyph.BitmapData = (unsigned int*)(buf_bitmap_buffers.back() + buf_bitmap_current_used_bytes); src_glyph.BitmapData = (unsigned int*)(buf_bitmap_buffers.back() + buf_bitmap_current_used_bytes);