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KVM: arm64: Drop last page ref in kvm_pgtable_stage2_free_removed()

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The reference count on page table allocations is increased for every
'counted' PTE (valid or donated) in the table in addition to the initial
reference from ->zalloc_page(). kvm_pgtable_stage2_free_removed() fails
to drop the last reference on the root of the table walk, meaning we
leak memory.

Fix it by dropping the last reference after the free walker returns,
at which point all references for 'counted' PTEs have been released.

Cc: stable@vger.kernel.org
Fixes: 5c359cca1f ("KVM: arm64: Tear down unlinked stage-2 subtree after break-before-make")
Reported-by: Yu Zhao <yuzhao@google.com>
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
Tested-by: Yu Zhao <yuzhao@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20230530193213.1663411-1-oliver.upton@linux.dev
This commit is contained in:
Oliver Upton 2023-05-30 19:32:13 +00:00 committed by Marc Zyngier
parent 811154e234
commit f6a27d6dc5
1 changed files with 3 additions and 0 deletions
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3
arch/arm64/kvm/hyp/pgtable.c
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@ -1332,4 +1332,7 @@ void kvm_pgtable_stage2_free_removed(struct kvm_pgtable_mm_ops *mm_ops, void *pg
}; };
WARN_ON(__kvm_pgtable_walk(&data, mm_ops, ptep, level + 1)); WARN_ON(__kvm_pgtable_walk(&data, mm_ops, ptep, level + 1));
WARN_ON(mm_ops->page_count(pgtable) != 1);
mm_ops->put_page(pgtable);
} }