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buffer: add bounds validation to SlowCopy and FastCopy #60264

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buffer: add bounds validation to SlowCopy and FastCopy #60264

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buffer: add bounds validation to SlowCopy and FastCopy
Rabie45 Oct 15, 2025
75cfdfb
Use IsArrayBufferView() and ByteLength() instead of Buffer::HasInstan…
Rabie45 Oct 15, 2025
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34 changes: 33 additions & 1 deletion src/node_buffer.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -578,17 +578,35 @@ void CopyImpl(Local<Value> source_obj,
void SlowCopy(const FunctionCallbackInfo<Value>& args) {
Local<Value> source_obj = args[0];
Local<Value> target_obj = args[1];
Isolate* isolate = args.GetIsolate();

// Add validation before call CopyImpl blindly
if (!source_obj->IsArrayBufferView() || !target_obj->IsArrayBufferView()) {
isolate->ThrowException(v8::Exception::TypeError(
String::NewFromUtf8Literal(isolate, "Arguments must be ArrayBufferViews")));
return;
}
const uint32_t target_start = args[2].As<Uint32>()->Value();
const uint32_t source_start = args[3].As<Uint32>()->Value();
const uint32_t to_copy = args[4].As<Uint32>()->Value();
size_t source_len = source_obj.As<ArrayBufferView>()->ByteLength();
size_t target_len = target_obj.As<ArrayBufferView>()->ByteLength();

if (source_start > source_len || target_start > target_len ||
to_copy > source_len - source_start ||
to_copy > target_len - target_start) {
isolate->ThrowException(v8::Exception::RangeError(
String::NewFromUtf8Literal(isolate, "Buffer copy out of range")));
return;
}

CopyImpl(source_obj, target_obj, target_start, source_start, to_copy);

args.GetReturnValue().Set(to_copy);
}

// Assume caller has properly validated args.
uint32_t FastCopy(Local<Value> receiver,
int32_t FastCopy(Local<Value> receiver,
Local<Value> source_obj,
Local<Value> target_obj,
uint32_t target_start,
Expand All @@ -597,7 +615,21 @@ uint32_t FastCopy(Local<Value> receiver,
// NOLINTNEXTLINE(runtime/references)
FastApiCallbackOptions& options) {
HandleScope scope(options.isolate);
Isolate* isolate = options.isolate;

if (!source_obj->IsArrayBufferView() || !target_obj->IsArrayBufferView()) {
isolate->ThrowException(v8::Exception::TypeError(
String::NewFromUtf8Literal(isolate, "Arguments must be ArrayBufferViews")));
return 0;
}
// Validate First before call CopyImpl blindly
size_t src_len = source_obj.As<ArrayBufferView>()->ByteLength();
size_t dst_len = target_obj.As<ArrayBufferView>()->ByteLength();

if (source_start > src_len || target_start > dst_len ||
to_copy > src_len - source_start || to_copy > dst_len - target_start) {
return -1;
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This still needs to be actually handled on the JS side, right?

}
CopyImpl(source_obj, target_obj, target_start, source_start, to_copy);

return to_copy;
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