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Kernel/VM: Make local_offset in PhysicalRegion::free_page_at unsigned
Anything above or equal to the 2 GB mark has the left most bit set (0x8000...), which was falsely interpreted as negative due to local_offset being signed. This makes it unsigned by using FlatPtr. To check for underflow as was intended, lets use Checked instead. Fixes #4585
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1 changed files with 5 additions and 4 deletions
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@ -156,11 +156,12 @@ void PhysicalRegion::free_page_at(PhysicalAddress addr)
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ASSERT_NOT_REACHED();
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}
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ptrdiff_t local_offset = addr.get() - m_lower.get();
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ASSERT(local_offset >= 0);
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ASSERT((FlatPtr)local_offset < (FlatPtr)(m_pages * PAGE_SIZE));
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Checked<FlatPtr> local_offset = addr.get();
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local_offset -= m_lower.get();
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ASSERT(!local_offset.has_overflow());
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ASSERT(local_offset.value() < (FlatPtr)(m_pages * PAGE_SIZE));
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auto page = (FlatPtr)local_offset / PAGE_SIZE;
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auto page = local_offset.value() / PAGE_SIZE;
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m_bitmap.set(page, false);
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m_free_hint = page; // We know we can find one here for sure
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m_used--;
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