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

5
arch/x86/kvm/vmx.c
View File

@@ -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 << 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))
@@ -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 &