From: Maxim Levitsky
stable inclusion
from linux-4.19.205
commit 42f4312c0e8a225b5f1e3ed029509ef514f2157a
category: bugfix
issue: #I4CBEA
CVE: CVE-2021-3653
--------------------------------
[ upstream commit 0f923e07124df069ba68d8bb12324398f4b6b709 ]
* Invert the mask of bits that we pick from L2 in
nested_vmcb02_prepare_control
* Invert and explicitly use VIRQ related bits bitmask in svm_clear_vintr
This fixes a security issue that allowed a malicious L1 to run L2 with
AVIC enabled, which allowed the L2 to exploit the uninitialized and enabled
AVIC to read/write the host physical memory at some offsets.
Fixes: 3d6368ef580a ("KVM: SVM: Add VMRUN handler")
Signed-off-by: Maxim Levitsky
Signed-off-by: Paolo Bonzini
Signed-off-by: Greg Kroah-Hartman
Signed-off-by: Yang Yingliang
Reviewed-by: Xiu Jianfeng
Signed-off-by: Yang Yingliang
Signed-off-by: Yu Changchun
---
arch/x86/include/asm/svm.h | 2 ++
arch/x86/kvm/svm.c | 15 ++++++++-------
2 files changed, 10 insertions(+), 7 deletions(-)
diff --git a/arch/x86/include/asm/svm.h b/arch/x86/include/asm/svm.h
index 93b462e48067..b6dedf6c835c 100644
--- a/arch/x86/include/asm/svm.h
+++ b/arch/x86/include/asm/svm.h
@@ -118,6 +118,8 @@ struct __attribute__ ((__packed__)) vmcb_control_area {
#define V_IGN_TPR_SHIFT 20
#define V_IGN_TPR_MASK (1 << V_IGN_TPR_SHIFT)
+#define V_IRQ_INJECTION_BITS_MASK (V_IRQ_MASK | V_INTR_PRIO_MASK | V_IGN_TPR_MASK)
+
#define V_INTR_MASKING_SHIFT 24
#define V_INTR_MASKING_MASK (1 << V_INTR_MASKING_SHIFT)
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 0ee036be892c..e5b6e76c1da2 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -1436,12 +1436,7 @@ static __init int svm_hardware_setup(void)
}
}
- if (vgif) {
- if (!boot_cpu_has(X86_FEATURE_VGIF))
- vgif = false;
- else
- pr_info("Virtual GIF supported\n");
- }
+ vgif = false; /* Disabled for CVE-2021-3653 */
return 0;
@@ -3575,7 +3570,13 @@ static void enter_svm_guest_mode(struct vcpu_svm *svm, u64 vmcb_gpa,
svm->nested.intercept = nested_vmcb->control.intercept;
svm_flush_tlb(&svm->vcpu, true);
- svm->vmcb->control.int_ctl = nested_vmcb->control.int_ctl | V_INTR_MASKING_MASK;
+
+ svm->vmcb->control.int_ctl &=
+ V_INTR_MASKING_MASK | V_GIF_ENABLE_MASK | V_GIF_MASK;
+
+ svm->vmcb->control.int_ctl |= nested_vmcb->control.int_ctl &
+ (V_TPR_MASK | V_IRQ_INJECTION_BITS_MASK);
+
if (nested_vmcb->control.int_ctl & V_INTR_MASKING_MASK)
svm->vcpu.arch.hflags |= HF_VINTR_MASK;
else
--
2.22.0
