Validate the effective type size of modules #215
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This commit implements a fix for bytecodealliance#214 where the effective size of the type of any item in a module (or a module itself) is now required to be bounded. The goal here is to accept reasonable modules but at the same time protecting implementations like wasmtime from having to worry about deeply recursive and nested module types. The general fix here is to account for the size of all types as we parse them, and at all times the size is bounded. Additionally wasm-smith is updated with similar accounting for the size of types and such to prevent generating modules with massively recursive types. Closes bytecodealliance#214
fitzgen
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alexcrichton
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Nov 16, 2022
…lliance#215) * Split out the `Option` and `Expected` types from `Variant` This commit is like prior PRs to split out specializations of types into their own AST type to avoid conflicting with the main type (in this case `variant`). I originally thought these two types would be relatively simple but this is probably one of the more complicated transitions, as evidenced by the lines changed here. The main churn was that variants already have a significant amount of code to support them and this is in some places "duplicating" code for option/expected and in other cases splitting what was already an if/else. Overall I think that the generated code gets a little better since it's clear when something is and `option` vs `expected` now rather than trying to have everything shoehorned into one. Notably the C code generator now generates descriptive fields like `bool is_some` or `bool is_err` instead of a bland `uint8_t tag` with some comments about how to use it. * Remove `Variant::as_{option,expected}` ... as these are separate variants now. * Review comments
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This commit implements a fix for #214 where the effective size of the
type of any item in a module (or a module itself) is now required to be
bounded. The goal here is to accept reasonable modules but at the same
time protecting implementations like wasmtime from having to worry about
deeply recursive and nested module types. The general fix here is to
account for the size of all types as we parse them, and at all times the
size is bounded.
Additionally wasm-smith is updated with similar accounting for the size
of types and such to prevent generating modules with massively recursive
types.
Closes #214