From ebbdf37ce9abb597015fa85df6630ebfa7d0a97f Mon Sep 17 00:00:00 2001 From: Pei Li Date: Thu, 27 Jun 2024 08:03:56 -0700 Subject: [PATCH] KVM: Validate hva in kvm_gpc_activate_hva() to fix __kvm_gpc_refresh() WARN Check that the virtual address is "ok" when activating a gfn_to_pfn_cache with a host VA to ensure that KVM never attempts to use a bad address. This fixes a bug where KVM fails to check the incoming address when handling KVM_XEN_VCPU_ATTR_TYPE_VCPU_INFO_HVA in kvm_xen_vcpu_set_attr(). Reported-by: syzbot+fd555292a1da3180fc82@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=fd555292a1da3180fc82 Tested-by: syzbot+fd555292a1da3180fc82@syzkaller.appspotmail.com Signed-off-by: Pei Li Reviewed-by: Paul Durrant Reviewed-by: David Woodhouse Link: https://lore.kernel.org/r/20240627-bug5-v2-1-2c63f7ee6739@gmail.com [sean: rewrite changelog with --verbose] Signed-off-by: Sean Christopherson --- arch/x86/kvm/xen.c | 2 +- virt/kvm/pfncache.c | 3 +++ 2 files changed, 4 insertions(+), 1 deletion(-) diff --git a/arch/x86/kvm/xen.c b/arch/x86/kvm/xen.c index f65b35a05d91..67bb4e89c399 100644 --- a/arch/x86/kvm/xen.c +++ b/arch/x86/kvm/xen.c @@ -741,7 +741,7 @@ int kvm_xen_hvm_set_attr(struct kvm *kvm, struct kvm_xen_hvm_attr *data) } else { void __user * hva = u64_to_user_ptr(data->u.shared_info.hva); - if (!PAGE_ALIGNED(hva) || !access_ok(hva, PAGE_SIZE)) { + if (!PAGE_ALIGNED(hva)) { r = -EINVAL; } else if (!hva) { kvm_gpc_deactivate(&kvm->arch.xen.shinfo_cache); diff --git a/virt/kvm/pfncache.c b/virt/kvm/pfncache.c index e3453e869e92..f0039efb9e1e 100644 --- a/virt/kvm/pfncache.c +++ b/virt/kvm/pfncache.c @@ -430,6 +430,9 @@ int kvm_gpc_activate(struct gfn_to_pfn_cache *gpc, gpa_t gpa, unsigned long len) int kvm_gpc_activate_hva(struct gfn_to_pfn_cache *gpc, unsigned long uhva, unsigned long len) { + if (!access_ok((void __user *)uhva, len)) + return -EINVAL; + return __kvm_gpc_activate(gpc, INVALID_GPA, uhva, len); }