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nodejs-github-bot merged 2 commits into from
Oct 2, 2026
Merged

ffi: throw on allocation failure in toArrayBuffer() #66406

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54907ac
ffi: throw on allocation failure in toArrayBuffer()
trivikr Sep 30, 2026
1d89180
fixup! ffi: throw on allocation failure in toArrayBuffer()
trivikr Sep 30, 2026
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ffi: throw on allocation failure in toArrayBuffer() 
The copy path of toArrayBuffer() allocated its backing store with
V8's default failure mode, so a large length aborted the process
with a fatal out-of-memory error. toBuffer() throws a catchable
ERR_MEMORY_ALLOCATION_FAILED for the same input.

Allocate with kReturnNull and throw ERR_MEMORY_ALLOCATION_FAILED
when the allocation fails. The memory is left uninitialized because
memcpy() fills it right after.

Signed-off-by: Trivikram Kamat <16024985+trivikr@users.noreply.github.com>
Assisted-by: claude:opus-5.5
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@trivikr
trivikr committed Sep 30, 2026
commit 54907ac7ba97691fce83078635c465bbf465c855
13 changes: 11 additions & 2 deletions src/ffi/data.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -15,6 +15,8 @@
using v8::ArrayBuffer;
using v8::ArrayBufferView;
using v8::BackingStore;
using v8::BackingStoreInitializationMode;
using v8::BackingStoreOnFailureMode;
using v8::BigInt;
using v8::FunctionCallbackInfo;
using v8::Integer;
Expand Down Expand Up @@ -670,8 +672,15 @@ void ToArrayBuffer(const FunctionCallbackInfo<Value>& args) {

Local<ArrayBuffer> ab;
if (copy) {
std::unique_ptr<BackingStore> store =
ArrayBuffer::NewBackingStore(isolate, len);
std::unique_ptr<BackingStore> store = ArrayBuffer::NewBackingStore(
isolate,
len,
BackingStoreInitializationMode::kUninitialized,
BackingStoreOnFailureMode::kReturnNull);
if (!store) [[unlikely]] {
THROW_ERR_MEMORY_ALLOCATION_FAILED(env);
return;
}
if (len > 0) memcpy(store->Data(), reinterpret_cast<void*>(ptr), len);
ab = ArrayBuffer::New(isolate, std::move(store));
} else {
Expand Down
10 changes: 10 additions & 0 deletions test/ffi/test-ffi-memory.js
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Expand Up @@ -371,6 +371,16 @@ test('ffi rejects unsafe integers as an offset or length', () => {
}));
});

test('ffi toBuffer and toArrayBuffer throw when the copy cannot be allocated', {
skip: (bufferConstants.MAX_LENGTH < 2 ** 50 && 'requires a 64-bit buffer length limit') ||
(common.isASan && 'ASan aborts on huge allocations'),
}, () => {
// The allocation fails before the source pointer is read.
const error = { code: 'ERR_MEMORY_ALLOCATION_FAILED' };
assert.throws(() => ffi.toBuffer(1n, 2 ** 50), error);
assert.throws(() => ffi.toArrayBuffer(1n, 2 ** 50), error);
});

test('ffi memory helpers reject missing required arguments', () => {
const widths = ['Int8', 'Uint8', 'Int16', 'Uint16', 'Int32', 'Uint32',
'Int64', 'Uint64', 'Float32', 'Float64'];
Expand Down