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cherry-pick fixes for CVE-2021-3653 and CVE-2021-3656

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from ubuntu-focal upstream/master-next

Signed-off-by: Stoiko Ivanov <s.ivanov@proxmox.com>
Signed-off-by: Wolfgang Bumiller <w.bumiller@proxmox.com>
This commit is contained in:
Stoiko Ivanov 2021-08-18 17:35:22 +02:00 committed by Wolfgang Bumiller
parent 916656976b
commit f290af2cd5
2 changed files with 127 additions and 0 deletions
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45
patches/kernel/0008-UBUNTU-SAUCE-KVM-nSVM-always-intercept-VMLOAD-VMSAVE.patch Normal file
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@ -0,0 +1,45 @@
From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Maxim Levitsky <mlevitsk@redhat.com>
Date: Thu, 29 Jul 2021 18:37:38 +0300
Subject: [PATCH] UBUNTU: SAUCE: KVM: nSVM: always intercept VMLOAD/VMSAVE when
nested
If L1 disables VMLOAD/VMSAVE intercepts, and doesn't enable
Virtual VMLOAD/VMSAVE (currently not supported for the nested hypervisor),
then VMLOAD/VMSAVE must operate on the L1 physical memory, which is only
possible by making L0 intercept these instructions.
Failure to do so allowed the nested guest to run VMLOAD/VMSAVE unintercepted,
and thus read/write portions of the host physical memory.
This fixes CVE-2021-3656, which was discovered by Maxim Levitsky and
Paolo Bonzini.
Fixes: 89c8a4984fc9 ("KVM: SVM: Enable Virtual VMLOAD VMSAVE feature")
Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
CVE-2021-3656
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
Acked-by: Stefan Bader <stefan.bader@canonical.com>
Acked-by: Ben Romer <benjamin.romer@canonical.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>
(cherry picked from commit 001ba8ebae0d2489b3e671b231daed4ad6f558d2)
Signed-off-by: Stoiko Ivanov <s.ivanov@proxmox.com>
---
arch/x86/kvm/svm.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index be8a017be58b..3b1b57521d8b 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -516,6 +516,9 @@ static void recalc_intercepts(struct vcpu_svm *svm)
c->intercept_dr = h->intercept_dr | g->intercept_dr;
c->intercept_exceptions = h->intercept_exceptions | g->intercept_exceptions;
c->intercept = h->intercept | g->intercept;
+
+ c->intercept |= (1ULL << INTERCEPT_VMLOAD);
+ c->intercept |= (1ULL << INTERCEPT_VMSAVE);
}
static inline struct vmcb *get_host_vmcb(struct vcpu_svm *svm)

82
patches/kernel/0009-KVM-nSVM-avoid-picking-up-unsupported-bits-from-L2-i.patch Normal file
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@ -0,0 +1,82 @@
From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Maxim Levitsky <mlevitsk@redhat.com>
Date: Mon, 16 Aug 2021 22:06:00 +0200
Subject: [PATCH] KVM: nSVM: avoid picking up unsupported bits from L2 in
int_ctl (CVE-2021-3653)
BugLink: https://bugs.launchpad.net/bugs/1940134
commit 0f923e07124df069ba68d8bb12324398f4b6b709 upstream.
* 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 <mlevitsk@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
(cherry picked from commit 4d9059df57cb3b8ff07cea55ba439fa3c846ef80 linux-5.4.y)
CVE-2021-3653
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
Acked-by: Kamal Mostafa <kamal@canonical.com>
Acked-by: Ian May <ian.may@canonical.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>
(cherry picked from commit 47aa9272b0ff29c845179e60ecf8cb7a8375b346)
Signed-off-by: Stoiko Ivanov <s.ivanov@proxmox.com>
---
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 6ece8561ba66..c29d8fb0ffbe 100644
--- a/arch/x86/include/asm/svm.h
+++ b/arch/x86/include/asm/svm.h
@@ -119,6 +119,8 @@ 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 3b1b57521d8b..4f2e4bc4b33b 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -1446,12 +1446,7 @@ 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;
@@ -3601,7 +3596,13 @@ 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