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Fix CodeValidator null deref after final END pops control stack #573

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Merged
titzer merged 3 commits into from
Mar 4, 2026
Merged

Fix CodeValidator null deref after final END pops control stack #573

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af0a44c
Fix CodeValidator null deref after final END pops control stack
sumleo Feb 13, 2026
7746380
Add regression test for empty control stack after final END
sumleo Mar 4, 2026
f9f9afa
Update CodeValidatorTest.v3
titzer Mar 4, 2026
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2 changes: 1 addition & 1 deletion src/engine/CodeValidator.v3
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Original file line number Diff line number Diff line change
Expand Up @@ -372,7 +372,7 @@ class CodeValidator(extensions: Extension.set, limits: Limits, module: Module, e
ctl_stack.pop();
if (validatingInitExpr && ctl_stack.empty()) { // END finished the init expr
codeptr.reset(codeptr.data, codeptr.pos, codeptr.pos);
} else {
} else if (!ctl_stack.empty()) {
ctl_top = ctl_stack.peek();
}
}
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6 changes: 6 additions & 0 deletions test/unittest/CodeValidatorTest.v3
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Expand Up @@ -100,6 +100,7 @@ def X_ = void(
T("simd.binop2", test_simd_binop2),
T("simd.binop3", test_simd_binop3),
T("memarg_stolen_is64", test_memarg_stolen_is64),
T("end_empty_ctl", test_end_empty_ctl),
()
);

Expand Down Expand Up @@ -2418,3 +2419,8 @@ def test_memarg_stolen_is64(t: CodeValidatorTester) {
if ((copy[pos] & BpConstants.MEMARG_STOLEN_IS64) == 0) return t.t.fail1("expected 0x%x flag to be set for memory64", BpConstants.MEMARG_STOLEN_IS64);
}
}

def test_end_empty_ctl(t: CodeValidatorTester) {
t.sig(SigCache.v_v);
t.invalid(WasmError.OOB_LABEL, [u8.!(Opcode.END.code)], 2);
}