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| author | Eric Northup <digitaleric@google.com> | 2015-11-03 18:03:53 +0100 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2015-11-10 12:06:24 +0100 |
| commit | 54a20552e1eae07aa240fa370a0293e006b5faed (patch) | |
| tree | 68f23011f566132ae1dc3351c30227d1f1b85dc0 /arch/x86/kvm/vmx.c | |
| parent | d0e536d89395ecd8ab78fe999dc4d6f5d140ce46 (diff) | |
| download | lwn-54a20552e1eae07aa240fa370a0293e006b5faed.tar.gz lwn-54a20552e1eae07aa240fa370a0293e006b5faed.zip | |
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>
Diffstat (limited to 'arch/x86/kvm/vmx.c')
| -rw-r--r-- | arch/x86/kvm/vmx.c | 5 |
1 files changed, 4 insertions, 1 deletions
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c index b765b036a048..89aaedd2a91d 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 << 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 & |