Memory flattening: Check for overflow #6233
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aheejin
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Jan 23, 2024
src/support/safe_math.h
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| #if !__has_builtin(__builtin_add_overflow) | ||
| template<typename T> bool __builtin_add_overflow(T a, T b, T* output) { | ||
| // Atm this only supports unsigned types. | ||
| static_assert(std::is_unsigned_v<T>); |
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Why does this support only unsigned types and what do you mean by LLVM-isms? If LLVM's version supports both, is there a reason why we wouldn't use that?
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By LLVM-isms I mean the code uses other LLVM headers and various llvm:: stuff so it isn't easy to extract the entire header. We could extract just the one function, I suppose, but it uses LLVM naming conventions (AddOverflow).
Detecting signed overflow is harder as it can't just be a+b > a as with unsigned (since the added value can be negative). I think it's just another comparison (looks like that's what LLVM does) but I didn't look into it.
tlively
reviewed
Jan 23, 2024
radekdoulik
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to dotnet/binaryen
that referenced
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Jul 12, 2024
Fixes a fuzz testcase for wasm-ctor-eval. Add the beginnings of a polyfill for stdckdint.h to help that.
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Fixes a fuzz testcase for wasm-ctor-eval.
Add the beginnings of a header for overflow detection. I took a quick look at LLVM's
after writing this and it has many LLVM-isms so it doesn't seem worth trying to
adapt theirs.