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[GC] Fix trapping on array.new_data of dropped segments of offset > 0 #7124

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Merged
merged 5 commits into from
Dec 2, 2024
Merged

[GC] Fix trapping on array.new_data of dropped segments of offset > 0 #7124

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b9ebaf4
fix
kripken Nov 27, 2024
4feeb90
overflow checks
kripken Nov 27, 2024
adf9f76
Update src/wasm-interpreter.h
kripken Nov 27, 2024
1cb421c
see if newer gcc avoids the warning
kripken Nov 27, 2024
1a277ad
workaround
kripken Nov 27, 2024
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15 changes: 12 additions & 3 deletions src/wasm-interpreter.h
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Original file line number Diff line number Diff line change
Expand Up @@ -4022,16 +4022,25 @@ class ModuleRunnerBase : public ExpressionRunner<SubType> {

const auto& seg = *wasm.getDataSegment(curr->segment);
auto elemBytes = element.getByteSize();
auto end = offset + size * elemBytes;
if ((size != 0ull && droppedDataSegments.count(curr->segment)) ||
end > seg.data.size()) {

#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wmaybe-uninitialized"

uint64_t end;
if (std::ckd_add(&end, offset, size * elemBytes) || end > seg.data.size()) {
trap("out of bounds segment access in array.new_data");
}
if (droppedDataSegments.count(curr->segment) && end > 0) {
trap("dropped segment access in array.new_data");
}
contents.reserve(size);
for (Index i = offset; i < end; i += elemBytes) {
auto addr = (void*)&seg.data[i];
contents.push_back(this->makeFromMemory(addr, element));
}

#pragma GCC diagnostic pop

return self()->makeGCData(std::move(contents), curr->type);
}
Flow visitArrayNewElem(ArrayNewElem* curr) {
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21 changes: 21 additions & 0 deletions test/lit/exec/array.wast
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Original file line number Diff line number Diff line change
Expand Up @@ -13,6 +13,8 @@

(elem $passive $func)

(data $data "a")

;; CHECK: [fuzz-exec] calling func
;; CHECK-NEXT: [fuzz-exec] note result: func => 1
(func $func (export "func") (result i32)
Expand Down Expand Up @@ -98,6 +100,21 @@
(i32.const 0)
)
)

;; CHECK: [fuzz-exec] calling drop_array.new_data
;; CHECK-NEXT: [trap dropped segment access in array.new_data]
(func $drop_array.new_data (export "drop_array.new_data")
;; Dropping the data segment causes the next instruction to trap, even though
;; the size there is 0, because the offset is > 0.
(data.drop $data)
(drop
(array.new_data $array $data
(i32.const 1)
(i32.const 0)
)
)
)

)
;; CHECK: [fuzz-exec] calling func
;; CHECK-NEXT: [fuzz-exec] note result: func => 1
Expand All @@ -115,6 +132,10 @@
;; CHECK: [fuzz-exec] calling init_active_in_bounds

;; CHECK: [fuzz-exec] calling init_passive

;; CHECK: [fuzz-exec] calling drop_array.new_data
;; CHECK-NEXT: [trap dropped segment access in array.new_data]
;; CHECK-NEXT: [fuzz-exec] comparing drop_array.new_data
;; CHECK-NEXT: [fuzz-exec] comparing func
;; CHECK-NEXT: [fuzz-exec] comparing init_active
;; CHECK-NEXT: [fuzz-exec] comparing init_active_in_bounds
Expand Down