From: Oliver Upton Date: Tue, 30 May 2023 19:32:13 +0000 (+0000) Subject: KVM: arm64: Drop last page ref in kvm_pgtable_stage2_free_removed() X-Git-Tag: v6.3.7~16 X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=e02e3f510d046e5afa1798a7cbfa001f7457da0f;p=users%2Fdwmw2%2Flinux.git KVM: arm64: Drop last page ref in kvm_pgtable_stage2_free_removed() commit f6a27d6dc51b288106adaf053cff9c9b9cc12c4e upstream. 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: 5c359cca1faf ("KVM: arm64: Tear down unlinked stage-2 subtree after break-before-make") Reported-by: Yu Zhao Signed-off-by: Oliver Upton Tested-by: Yu Zhao Signed-off-by: Marc Zyngier Link: https://lore.kernel.org/r/20230530193213.1663411-1-oliver.upton@linux.dev Signed-off-by: Greg Kroah-Hartman --- diff --git a/arch/arm64/kvm/hyp/pgtable.c b/arch/arm64/kvm/hyp/pgtable.c index faddf1e71c8de..acd233e5586a4 100644 --- a/arch/arm64/kvm/hyp/pgtable.c +++ b/arch/arm64/kvm/hyp/pgtable.c @@ -1333,4 +1333,7 @@ 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(mm_ops->page_count(pgtable) != 1); + mm_ops->put_page(pgtable); }