fix: kernel: move level parameter count and thm-is-prop checks for robustness#12817
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fix: kernel: move level parameter count and thm-is-prop checks for robustness#12817
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The kernel would crash (access uninitialized memory) when `is_delta` succeeded for a constant whose supplied universe-level count did not match its declaration's level-parameter count. `unfold_definition_core` had the count check, so it returned `none_expr()` in that case. Call sites in `lazy_delta_reduction_step` unconditionally dereferenced that result, causing undefined behaviour (garbled error or SIGSEGV). Fix: add the level-parameter-count check to `is_delta` and remove the now- redundant check from `unfold_definition_core`. This establishes the invariant: if `is_delta` succeeds then `unfold_definition` will also succeed. Add a regression test from the fuzzer-discovered reproducer in #10577. Co-authored-by: nomeata <148037+nomeata@users.noreply.github.com>
Co-authored-by: nomeata <148037+nomeata@users.noreply.github.com>
…o .gitignore Co-authored-by: nomeata <148037+nomeata@users.noreply.github.com>
Co-authored-by: nomeata <148037+nomeata@users.noreply.github.com>
…or robustness Co-authored-by: nomeata <148037+nomeata@users.noreply.github.com>
Co-authored-by: nomeata <148037+nomeata@users.noreply.github.com>
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This PR moves the universe-level-count check from
unfold_definition_coreintois_delta, establishing the invariant that ifis_deltasucceeds thenunfold_definitionalso succeeds. This prevents a crash (SIGSEGV or garbled error) that occurred when call sites inlazy_delta_reduction_stepunconditionally dereferenced the result ofunfold_definitioneven on a level-parameter-count mismatch.Additionally, moves the
is_propcheck for theorem types inadd_theoremto occur aftercheck_constant_val, so the type is verified to be well-formed beforeis_propevaluates it. This preventsis_propfrom being called on an ill-typed term when a malformed theorem declaration is supplied.Fixes #10577.