KVM: x86: Fix potential divide by 0 in lapic (CVE-2013-6367)
Under guest controllable circumstances apic_get_tmcct will execute a divide by zero and cause a crash. If the guest cpuid support tsc deadline timers and performs the following sequence of requests the host will crash. - Set the mode to periodic - Set the TMICT to 0 - Set the mode bits to 11 (neither periodic, nor one shot, nor tsc deadline) - Set the TMICT to non-zero. Then the lapic_timer.period will be 0, but the TMICT will not be. If the guest then reads from the TMCCT then the host will perform a divide by 0. This patch ensures that if the lapic_timer.period is 0, then the division does not occur. Reported-by: NAndrew Honig <ahonig@google.com> Cc: stable@vger.kernel.org Signed-off-by: NAndrew Honig <ahonig@google.com> Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Showing
想要评论请 注册 或 登录