From b963a22e6d1a266a67e9eecc88134713fd54775c Mon Sep 17 00:00:00 2001 From: Andy Honig Date: Tue, 19 Nov 2013 14:12:18 -0800 Subject: [PATCH] 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: Andrew Honig Cc: stable@vger.kernel.org Signed-off-by: Andrew Honig Signed-off-by: Paolo Bonzini --- Reading git-format-patch failed