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https://github.com/RGBCube/serenity
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b6d4eea7ac
Instead of returning HeapBlock memory to the kernel (or a non-type specific shared cache), we now keep a BlockAllocator per CellAllocator and implement "deallocation" by basically informing the kernel that we don't need the physical memory right now. This is done with MADV_FREE or MADV_DONTNEED if available, but for other platforms (including SerenityOS) we munmap and then re-mmap the memory to achieve the same effect. It's definitely clunky, so I've added a FIXME about implementing the madvise options on SerenityOS too. The important outcome of this change is that GC types that use a type-specific allocator become immune to use-after-free type confusion attacks, since their virtual addresses will only ever be re-used for the same exact type again and again. Fixes #22274
26 lines
407 B
C++
26 lines
407 B
C++
/*
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* Copyright (c) 2021-2023, Andreas Kling <kling@serenityos.org>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#pragma once
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#include <AK/Vector.h>
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#include <LibJS/Forward.h>
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namespace JS {
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class BlockAllocator {
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public:
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BlockAllocator() = default;
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~BlockAllocator();
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void* allocate_block(char const* name);
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void deallocate_block(void*);
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private:
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Vector<void*> m_blocks;
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};
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}
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