On Sun, Dec 22, 2013 at 12:56:49PM -0200, Marcelo Tosatti wrote:
> On Sun, Dec 22, 2013 at 11:17:21AM +0200, Rom Freiman wrote:
> > Hello everyone,
> >
> > I've been chasing this bug for a while.
> >
> > According to my research, this bug fix is works fine for
> > 3.11.9-200.fc19.x86_64 kernel version (and I also came to almost similar
> > solution and really solved the crash).
> >
> > But, the problem is, that it seems that this patch does not work on 3.13.0-rc2+
> > - it looks like the code flow is different and it crashes in ept_page_fault
> > and does not reach __direct_map:
>
> Yep, similar problem, care to send a patch against
>
> FNAME(page_fault), kvm_mmu_get_spte_hierarchy
>
> Maybe there are more vulnerable sites, should secure them all.
These should cover all it?
diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 31a5702..e50425d 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -2832,6 +2832,9 @@ static bool fast_page_fault(struct kvm_vcpu *vcpu, gva_t gva, int level,
bool ret = false;
u64 spte = 0ull;
+ if (!VALID_PAGE(vcpu->arch.mmu.root_hpa))
+ return false;
+
if (!page_fault_can_be_fast(error_code))
return false;
@@ -3227,6 +3230,9 @@ static u64 walk_shadow_page_get_mmio_spte(struct kvm_vcpu *vcpu, u64 addr)
struct kvm_shadow_walk_iterator iterator;
u64 spte = 0ull;
+ if (!VALID_PAGE(vcpu->arch.mmu.root_hpa))
+ return spte;
+
walk_shadow_page_lockless_begin(vcpu);
for_each_shadow_entry_lockless(vcpu, addr, iterator, spte)
if (!is_shadow_present_pte(spte))
@@ -4513,6 +4519,9 @@ int kvm_mmu_get_spte_hierarchy(struct kvm_vcpu *vcpu, u64 addr, u64 sptes[4])
u64 spte;
int nr_sptes = 0;
+ if (!VALID_PAGE(vcpu->arch.mmu.root_hpa))
+ return nr_sptes;
+
walk_shadow_page_lockless_begin(vcpu);
for_each_shadow_entry_lockless(vcpu, addr, iterator, spte) {
sptes[iterator.level-1] = spte;
diff --git a/arch/x86/kvm/paging_tmpl.h b/arch/x86/kvm/paging_tmpl.h
index ad75d77..cba218a 100644
--- a/arch/x86/kvm/paging_tmpl.h
+++ b/arch/x86/kvm/paging_tmpl.h
@@ -569,6 +569,9 @@ static int FNAME(fetch)(struct kvm_vcpu *vcpu, gva_t addr,
if (FNAME(gpte_changed)(vcpu, gw, top_level))
goto out_gpte_changed;
+ if (!VALID_PAGE(vcpu->arch.mmu.root_hpa))
+ goto out_gpte_changed;
+
for (shadow_walk_init(&it, vcpu, addr);
shadow_walk_okay(&it) && it.level > gw->level;
shadow_walk_next(&it)) {
@@ -820,6 +823,11 @@ static void FNAME(invlpg)(struct kvm_vcpu *vcpu, gva_t gva)
*/
mmu_topup_memory_caches(vcpu);
+ if (!VALID_PAGE(vcpu->arch.mmu.root_hpa)) {
+ WARN_ON(1);
+ return;
+ }
+
spin_lock(&vcpu->kvm->mmu_lock);
for_each_shadow_entry(vcpu, gva, iterator) {
level = iterator.level;
--
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