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Properly validate ref.cast when lacking a common supertype #6741

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merged 5 commits into from
Jul 23, 2024
Merged

Properly validate ref.cast when lacking a common supertype #6741

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7530b27
fix
kripken Jul 12, 2024
38e1ba9
fix
kripken Jul 12, 2024
6006c19
Merge remote-tracking branch 'origin/main' into ref.cast.val.unreach
kripken Jul 23, 2024
3abe58a
feedback: add test
kripken Jul 23, 2024
459552f
format
kripken Jul 23, 2024
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15 changes: 15 additions & 0 deletions src/wasm/wasm-validator.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -2780,6 +2780,21 @@ void FunctionValidator::visitRefCast(RefCast* curr) {
curr->ref->type.isRef(), curr, "ref.cast ref must have ref type")) {
return;
}
// If the cast is unreachable but not the ref (we ruled out the former
// earlier), then the cast is unreachable because the cast type had no
// common supertype with the ref, which is invalid. This is the same as the
// check below us, but we must do it first (as getHeapType fails otherwise).
if (!shouldBeUnequal(
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We could tighten this up even more by checking that the result type is a reference type. So if it somehow was set to i32 or something, we would still avoid the assertion failure.

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Sounds good, I added that now as an extra test (it has a more generic error message, and I didn't want to lose the specific explanation for the supertype issue).

curr->type,
Type(Type::unreachable),
curr,
"ref.cast target type and ref type must have a common supertype")) {
return;
}
// Also error (more generically) on i32 and anything else invalid here.
if (!shouldBeTrue(curr->type.isRef(), curr, "ref.cast must have ref type")) {
return;
}
shouldBeEqual(
curr->type.getHeapType().getBottom(),
curr->ref->type.getHeapType().getBottom(),
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10 changes: 10 additions & 0 deletions test/spec/ref_cast.wast
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Original file line number Diff line number Diff line change
Expand Up @@ -170,6 +170,16 @@
"common supertype"
)

(assert_invalid
(module
(type $t0 (struct))
(func (export "test-ref-cast-extern") (result anyref)
(ref.cast (ref extern) (struct.new $t0))
)
)
"common supertype"
)

(assert_malformed
(module quote "(func (ref.cast i32 (unreachable)))")
"expected reftype"
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