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https://github.com/LadybirdBrowser/ladybird
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b9ec043b5a
Maintain a HashTable<HeapBlock*> of live heap blocks in the Heap, updated on block creation and destruction. Weak containers (WeakMap, WeakSet, WeakRef, FinalizationRegistry) now check block liveness before accessing cell memory in their remove_dead_cells() methods. This prevents use-after-free when blocks have been freed during incremental sweeping.
70 lines
2.0 KiB
C++
70 lines
2.0 KiB
C++
/*
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* Copyright (c) 2021, Idan Horowitz <idan.horowitz@serenityos.org>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#include <LibGC/HeapBlock.h>
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#include <LibJS/Runtime/ExternalMemory.h>
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#include <LibJS/Runtime/WeakSet.h>
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namespace JS {
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GC_DEFINE_ALLOCATOR(WeakSet);
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GC::Ref<WeakSet> WeakSet::create(Realm& realm)
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{
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return realm.create<WeakSet>(realm.intrinsics().weak_set_prototype());
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}
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WeakSet::WeakSet(Object& prototype)
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: Object(ConstructWithPrototypeTag::Tag, prototype)
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, WeakContainer(heap())
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{
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}
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bool WeakSet::weak_set_has(GC::Ptr<Cell> value) const
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{
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return m_values.contains(value);
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}
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void WeakSet::weak_set_add(GC::Ptr<Cell> value)
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{
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auto old_external_memory_size = external_memory_size();
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m_values.set(value, AK::HashSetExistingEntryBehavior::Keep);
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account_external_memory_change(old_external_memory_size);
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}
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bool WeakSet::weak_set_remove(GC::Ptr<Cell> value)
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{
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auto old_external_memory_size = external_memory_size();
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auto did_remove = m_values.remove(value);
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if (did_remove)
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account_external_memory_change(old_external_memory_size);
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return did_remove;
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}
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void WeakSet::remove_dead_cells(Badge<GC::Heap>)
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{
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m_values.remove_all_matching([this](Cell* cell) {
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auto* block = GC::HeapBlock::from_cell(cell);
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return !heap().is_live_heap_block(block) || cell->state() != Cell::State::Live || !cell->is_marked();
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});
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}
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size_t WeakSet::external_memory_size() const
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{
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return saturating_add_external_memory_size(Object::external_memory_size(), hash_table_external_memory_size(m_values));
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}
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void WeakSet::account_external_memory_change(size_t old_external_memory_size)
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{
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auto new_external_memory_size = external_memory_size();
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if (new_external_memory_size > old_external_memory_size)
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heap().did_allocate_external_memory(new_external_memory_size - old_external_memory_size);
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else if (old_external_memory_size > new_external_memory_size)
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heap().did_free_external_memory(old_external_memory_size - new_external_memory_size);
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}
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}
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