From 79593c086eb95eb2886f36ee6f78a1d6845e1bdf Mon Sep 17 00:00:00 2001
From: David Woodhouse <dwmw@amazon.co.uk>
Date: Tue, 29 Mar 2022 13:11:47 -0400
Subject: [PATCH] KVM: avoid double put_page with gfn-to-pfn cache
If the cache's user host virtual address becomes invalid, there
is still a path from kvm_gfn_to_pfn_cache_refresh() where __release_gpc()
could release the pfn but the gpc->pfn field has not been overwritten
with an error value. If this happens, kvm_gfn_to_pfn_cache_unmap will
call put_page again on the same page.
Cc: stable@vger.kernel.org
Fixes: 982ed0de4753 ("KVM: Reinstate gfn_to_pfn_cache with invalidation support")
Signed-off-by: David Woodhouse <dwmw2@infradead.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
virt/kvm/pfncache.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/virt/kvm/pfncache.c b/virt/kvm/pfncache.c
index ce878f4be4daa..1621f8efd9616 100644
--- a/virt/kvm/pfncache.c
+++ b/virt/kvm/pfncache.c
@@ -191,6 +191,7 @@ int kvm_gfn_to_pfn_cache_refresh(struct kvm *kvm, struct gfn_to_pfn_cache *gpc,
gpc->uhva = gfn_to_hva_memslot(gpc->memslot, gfn);
if (kvm_is_error_hva(gpc->uhva)) {
+ gpc->pfn = KVM_PFN_ERR_FAULT;
ret = -EFAULT;
goto out;
}
--
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