From 5762cb10235776dd1ed5f5f9d6c1aff2b73bec5c Mon Sep 17 00:00:00 2001
From: Sean Christopherson <seanjc@google.com>
Date: Thu, 13 Oct 2022 21:12:30 +0000
Subject: [PATCH] KVM: Do not partially reinitialize gfn=>pfn cache during
activation
Don't partially reinitialize a gfn=>pfn cache when activating the cache,
and instead assert that the cache is not valid during activation. Bug
the VM if the assertion fails, as use-after-free and/or data corruption
is all but guaranteed if KVM ends up with a valid-but-inactive cache.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
---
virt/kvm/pfncache.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/virt/kvm/pfncache.c b/virt/kvm/pfncache.c
index 5b25127936915..c1a772cedc4bd 100644
--- a/virt/kvm/pfncache.c
+++ b/virt/kvm/pfncache.c
@@ -345,6 +345,8 @@ void kvm_gpc_init(struct gfn_to_pfn_cache *gpc, struct kvm *kvm,
gpc->kvm = kvm;
gpc->vcpu = vcpu;
gpc->usage = usage;
+ gpc->pfn = KVM_PFN_ERR_FAULT;
+ gpc->uhva = KVM_HVA_ERR_BAD;
}
EXPORT_SYMBOL_GPL(kvm_gpc_init);
@@ -353,10 +355,8 @@ int kvm_gpc_activate(struct gfn_to_pfn_cache *gpc, gpa_t gpa, unsigned long len)
struct kvm *kvm = gpc->kvm;
if (!gpc->active) {
- gpc->khva = NULL;
- gpc->pfn = KVM_PFN_ERR_FAULT;
- gpc->uhva = KVM_HVA_ERR_BAD;
- gpc->valid = false;
+ if (KVM_BUG_ON(gpc->valid, kvm))
+ return -EIO;
spin_lock(&kvm->gpc_lock);
list_add(&gpc->list, &kvm->gpc_list);
--
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