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Kernel: Don't unregister Region from RegionTree *before* unmapping it

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If we unregister from the RegionTree before unmapping, there's a race
where a new region can get inserted at the same address that we're about
to unmap. If this happens, ~Region() will then unmap the newly inserted
region, which now finds itself with cleared-out page table entries.
This commit is contained in:
Andreas Kling 2022-04-05 13:46:50 +02:00
parent a3db0ab14f
commit 0a83c03546
1 changed files with 3 additions and 3 deletions
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6
Kernel/Memory/Region.cpp
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@ -64,9 +64,6 @@ Region::~Region()
m_vmobject->remove_region(*this);
if (is_kernel())
MM.unregister_kernel_region(*this);
if (m_page_directory) {
SpinlockLocker pd_locker(m_page_directory->get_lock());
if (!is_readable() && !is_writable() && !is_executable()) {
@ -77,6 +74,9 @@ Region::~Region()
VERIFY(!m_page_directory);
}
}
if (is_kernel())
MM.unregister_kernel_region(*this);
}
ErrorOr<NonnullOwnPtr<Region>> Region::create_unbacked()