From: Paolo Bonzini pbonzini@redhat.com
stable inclusion from stable-v5.10.115 commit 9c8474fa3477395e754687b3edb17ca0dfe46d6a category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I5IZ9C
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=...
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[ Upstream commit 9191b8f0745e63edf519e4a54a4aaae1d3d46fbd ]
WARN and bail if KVM attempts to free a root that isn't backed by a shadow page. KVM allocates a bare page for "special" roots, e.g. when using PAE paging or shadowing 2/3/4-level page tables with 4/5-level, and so root_hpa will be valid but won't be backed by a shadow page. It's all too easy to blindly call mmu_free_root_page() on root_hpa, be nice and WARN instead of crashing KVM and possibly the kernel.
Reviewed-by: Sean Christopherson seanjc@google.com Signed-off-by: Paolo Bonzini pbonzini@redhat.com Signed-off-by: Sasha Levin sashal@kernel.org Signed-off-by: Zheng Zengkai zhengzengkai@huawei.com Acked-by: Xie XiuQi xiexiuqi@huawei.com --- arch/x86/kvm/mmu/mmu.c | 2 ++ 1 file changed, 2 insertions(+)
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c index 99ae11011ed4..bcf1bd9424f2 100755 --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c @@ -3140,6 +3140,8 @@ static void mmu_free_root_page(struct kvm *kvm, hpa_t *root_hpa, return;
sp = to_shadow_page(*root_hpa & PT64_BASE_ADDR_MASK); + if (WARN_ON(!sp)) + return;
if (kvm_mmu_put_root(kvm, sp)) { if (sp->tdp_mmu_page)