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ffi: avoid memcpy() with a null pointer #66200

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Merged
nodejs-github-bot merged 1 commit into from
Sep 24, 2026
Merged

ffi: avoid memcpy() with a null pointer #66200

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6 changes: 4 additions & 2 deletions src/ffi/data.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -662,7 +662,7 @@ void ToArrayBuffer(const FunctionCallbackInfo<Value>& args) {
if (copy) {
std::unique_ptr<BackingStore> store =
ArrayBuffer::NewBackingStore(isolate, len);
memcpy(store->Data(), reinterpret_cast<void*>(ptr), len);
if (len > 0) memcpy(store->Data(), reinterpret_cast<void*>(ptr), len);
ab = ArrayBuffer::New(isolate, std::move(store));
} else {
std::unique_ptr<BackingStore> store = ArrayBuffer::NewBackingStore(
Expand Down Expand Up @@ -740,7 +740,9 @@ void ExportBytes(const FunctionCallbackInfo<Value>& args) {
return;
}

std::memcpy(reinterpret_cast<void*>(ptr), view.data(), view.length());
if (view.length() > 0) {
std::memcpy(reinterpret_cast<void*>(ptr), view.data(), view.length());
}
}

void GetRawPointer(const FunctionCallbackInfo<Value>& args) {
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8 changes: 8 additions & 0 deletions test/ffi/test-ffi-memory.js
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Expand Up @@ -243,6 +243,14 @@ test('ffi toString returns null for a null pointer', () => {
assert.strictEqual(ffi.toString(0n), null);
});

test('ffi accepts zero-length copies through a null pointer', () => {
assert.strictEqual(ffi.toBuffer(0n, 0).length, 0);
assert.strictEqual(ffi.toArrayBuffer(0n, 0).byteLength, 0);
assert.strictEqual(ffi.exportBuffer(Buffer.alloc(0), 0n, 0), undefined);
assert.strictEqual(ffi.exportArrayBuffer(new ArrayBuffer(0), 0n, 0), undefined);
assert.strictEqual(ffi.exportArrayBufferView(new Uint8Array(0), 0n, 0), undefined);
});

test('ffi validates memory access arguments', () => {
withAllocations(common.mustCall((alloc) => {
const ptr = alloc(8);
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