diff options
Diffstat (limited to 'freed-ora/current/f21/KVM-x86-work-around-infinite-loop-in-microcode-when-.patch')
| -rw-r--r-- | freed-ora/current/f21/KVM-x86-work-around-infinite-loop-in-microcode-when-.patch | 92 |
1 files changed, 92 insertions, 0 deletions
diff --git a/freed-ora/current/f21/KVM-x86-work-around-infinite-loop-in-microcode-when-.patch b/freed-ora/current/f21/KVM-x86-work-around-infinite-loop-in-microcode-when-.patch new file mode 100644 index 000000000..013af11e1 --- /dev/null +++ b/freed-ora/current/f21/KVM-x86-work-around-infinite-loop-in-microcode-when-.patch @@ -0,0 +1,92 @@ +From adceca1789584fe567828afb7246bd35a8549e94 Mon Sep 17 00:00:00 2001 +From: Eric Northup <digitaleric@google.com> +Date: Tue, 10 Nov 2015 13:22:52 +0100 +Subject: [PATCH 1/2] KVM: x86: work around infinite loop in microcode when #AC + is delivered + +It was found that a guest can DoS a host by triggering an infinite +stream of "alignment check" (#AC) exceptions. This causes the +microcode to enter an infinite loop where the core never receives +another interrupt. The host kernel panics pretty quickly due to the +effects (CVE-2015-5307). + +Signed-off-by: Eric Northup <digitaleric@google.com> +Cc: stable@vger.kernel.org +Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> +--- + arch/x86/include/uapi/asm/svm.h | 1 + + arch/x86/kvm/svm.c | 8 ++++++++ + arch/x86/kvm/vmx.c | 5 ++++- + 3 files changed, 13 insertions(+), 1 deletion(-) + +diff --git a/arch/x86/include/uapi/asm/svm.h b/arch/x86/include/uapi/asm/svm.h +index b5d7640abc5d..8a4add8e4639 100644 +--- a/arch/x86/include/uapi/asm/svm.h ++++ b/arch/x86/include/uapi/asm/svm.h +@@ -100,6 +100,7 @@ + { SVM_EXIT_EXCP_BASE + UD_VECTOR, "UD excp" }, \ + { SVM_EXIT_EXCP_BASE + PF_VECTOR, "PF excp" }, \ + { SVM_EXIT_EXCP_BASE + NM_VECTOR, "NM excp" }, \ ++ { SVM_EXIT_EXCP_BASE + AC_VECTOR, "AC excp" }, \ + { SVM_EXIT_EXCP_BASE + MC_VECTOR, "MC excp" }, \ + { SVM_EXIT_INTR, "interrupt" }, \ + { SVM_EXIT_NMI, "nmi" }, \ +diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c +index f2c8e4917688..7203b3cc71b5 100644 +--- a/arch/x86/kvm/svm.c ++++ b/arch/x86/kvm/svm.c +@@ -1110,6 +1110,7 @@ static void init_vmcb(struct vcpu_svm *svm) + set_exception_intercept(svm, PF_VECTOR); + set_exception_intercept(svm, UD_VECTOR); + set_exception_intercept(svm, MC_VECTOR); ++ set_exception_intercept(svm, AC_VECTOR); + + set_intercept(svm, INTERCEPT_INTR); + set_intercept(svm, INTERCEPT_NMI); +@@ -1798,6 +1799,12 @@ static int ud_interception(struct vcpu_svm *svm) + return 1; + } + ++static int ac_interception(struct vcpu_svm *svm) ++{ ++ kvm_queue_exception_e(&svm->vcpu, AC_VECTOR, 0); ++ return 1; ++} ++ + static void svm_fpu_activate(struct kvm_vcpu *vcpu) + { + struct vcpu_svm *svm = to_svm(vcpu); +@@ -3362,6 +3369,7 @@ static int (*const svm_exit_handlers[])(struct vcpu_svm *svm) = { + [SVM_EXIT_EXCP_BASE + PF_VECTOR] = pf_interception, + [SVM_EXIT_EXCP_BASE + NM_VECTOR] = nm_interception, + [SVM_EXIT_EXCP_BASE + MC_VECTOR] = mc_interception, ++ [SVM_EXIT_EXCP_BASE + AC_VECTOR] = ac_interception, + [SVM_EXIT_INTR] = intr_interception, + [SVM_EXIT_NMI] = nmi_interception, + [SVM_EXIT_SMI] = nop_on_interception, +diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c +index 5eb56ed77c1f..106aa940d3c0 100644 +--- a/arch/x86/kvm/vmx.c ++++ b/arch/x86/kvm/vmx.c +@@ -1631,7 +1631,7 @@ static void update_exception_bitmap(struct kvm_vcpu *vcpu) + u32 eb; + + eb = (1u << PF_VECTOR) | (1u << UD_VECTOR) | (1u << MC_VECTOR) | +- (1u << NM_VECTOR) | (1u << DB_VECTOR); ++ (1u << NM_VECTOR) | (1u << DB_VECTOR) | (1u << AC_VECTOR); + if ((vcpu->guest_debug & + (KVM_GUESTDBG_ENABLE | KVM_GUESTDBG_USE_SW_BP)) == + (KVM_GUESTDBG_ENABLE | KVM_GUESTDBG_USE_SW_BP)) +@@ -5266,6 +5266,9 @@ static int handle_exception(struct kvm_vcpu *vcpu) + return handle_rmode_exception(vcpu, ex_no, error_code); + + switch (ex_no) { ++ case AC_VECTOR: ++ kvm_queue_exception_e(vcpu, AC_VECTOR, error_code); ++ return 1; + case DB_VECTOR: + dr6 = vmcs_readl(EXIT_QUALIFICATION); + if (!(vcpu->guest_debug & +-- +2.4.3 + |
