imgui_freetype: Assert if bitmap size exceed chunk size to avoid buffer overflow. (#5731)
diff --git a/misc/freetype/imgui_freetype.cpp b/misc/freetype/imgui_freetype.cpp
index 4066a9a..0325532 100644
--- a/misc/freetype/imgui_freetype.cpp
+++ b/misc/freetype/imgui_freetype.cpp
@@ -508,7 +508,7 @@
// Allocate temporary rasterization data buffers.
// 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)
- // 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;
int buf_bitmap_current_used_bytes = 0;
ImVector<unsigned char*> buf_bitmap_buffers;
@@ -556,6 +556,7 @@
buf_bitmap_current_used_bytes = 0;
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.
src_glyph.BitmapData = (unsigned int*)(buf_bitmap_buffers.back() + buf_bitmap_current_used_bytes);
