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Fix integer overflow in computeBindingSize for glTF accessors #9841

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Fix integer overflow in computeBindingSize for glTF accessors #9841

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15 changes: 14 additions & 1 deletion libs/gltfio/src/Utility.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -168,7 +168,20 @@ bool primitiveHasVertexColor(cgltf_primitive* inPrim) {
// private but its implementation file is available in this cpp file.
uint32_t computeBindingSize(cgltf_accessor const* accessor) {
cgltf_size element_size = cgltf_calc_size(accessor->type, accessor->component_type);
return uint32_t(accessor->stride * (accessor->count - 1) + element_size);
// Validate against overflow, consistent with the check in decodeMeshoptCompression above.
FILAMENT_CHECK_POSTCONDITION(accessor->count > 0)
<< "gltfio: accessor count must be > 0";
cgltf_size const countMinus1 = accessor->count - 1;
if (accessor->stride > 0) {
cgltf_size const maxCount = std::numeric_limits<cgltf_size>::max() / accessor->stride;
FILAMENT_CHECK_POSTCONDITION(countMinus1 <= maxCount)
<< "gltfio: binding size overflow (stride=" << accessor->stride
<< ", count=" << accessor->count << ")";
}
cgltf_size const result = accessor->stride * countMinus1 + element_size;
FILAMENT_CHECK_POSTCONDITION(result <= std::numeric_limits<uint32_t>::max())
<< "gltfio: binding size exceeds uint32_t max";
return uint32_t(result);
}

void convertBytesToShorts(uint16_t* dst, uint8_t const* src, size_t count) {
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