update to vzkernel-2.6.32-042stab113.17.src.rpm

[pve-kernel-2.6.32.git] / infinite-loop-fix.patch

commit 54a20552e1eae07aa240fa370a0293e006b5faed
Author: Eric Northup <digitaleric@google.com>
Date:   Tue Nov 3 18:03:53 2015 +0100

    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>

diff --git a/arch/x86/include/asm/kvm.h b/arch/x86/include/asm/kvm.h
--- a/arch/x86/include/asm/kvm.h
+++ b/arch/x86/include/asm/kvm.h
@@ -23,6 +23,7 @@
 #define GP_VECTOR 13
 #define PF_VECTOR 14
 #define MF_VECTOR 16
+#define AC_VECTOR 17
 #define MC_VECTOR 18
 
 /* Select x86 specific features in <linux/kvm.h> */
diff --git a/arch/x86/include/uapi/asm/svm.h b/arch/x86/include/uapi/asm/svm.h
index b5d7640..8a4add8 100644
--- a/arch/x86/include/asm/svm.h
+++ b/arch/x86/include/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 f2ba919..1839264 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -1019,7 +1019,8 @@ static void init_vmcb(struct vcpu_svm *svm)
 
 control->intercept_exceptions = (1 << PF_VECTOR) |
 					(1 << UD_VECTOR) |
-					(1 << MC_VECTOR);
+					(1 << MC_VECTOR) |
+					(1 << AC_VECTOR);
 
 	control->intercept = 	(1ULL << INTERCEPT_INTR) |
 				(1ULL << INTERCEPT_NMI) |
@@ -1707,6 +1708,12 @@ 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 int nm_interception(struct vcpu_svm *svm)
 {
 	svm->vmcb->control.intercept_exceptions &= ~(1 << NM_VECTOR);
@@ -3270,6 +3277,7 @@ 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 b765b03..89aaedd 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -1639,7 +1639,7 @@ 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 << NM_VECTOR) | (1u << AC_VECTOR);
 	/*
 	 * Unconditionally intercept #DB so we can maintain dr6 without
 	 * reading it every exit.
@@ -5261,6 +5261,9 @@ 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 &