xiaomi-sm8450/android_kernel_xiaomi_sm8450
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

KVM: x86: work around infinite loop in microcode when #AC is delivered

Browse Source 
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>
This commit is contained in:
Eric Northup
2015-11-03 18:03:53 +01:00
committed by Paolo Bonzini
parent d0e536d893
commit 54a20552e1
3 changed files with 13 additions and 1 deletions
Download Patch File Download Diff File Expand all files Collapse all files

8
arch/x86/kvm/svm.c
View File

@@ -1019,6 +1019,7 @@ 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);
@@ -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 void svm_fpu_activate(struct kvm_vcpu *vcpu)
{
struct vcpu_svm *svm = to_svm(vcpu);
@@ -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,