From: Andy Honig Date: Tue, 19 Nov 2013 22:12:18 +0000 (-0800) Subject: KVM: x86: Fix potential divide by 0 in lapic (CVE-2013-6367) X-Git-Tag: v3.2.54~43 X-Git-Url: https://git.openpandora.org/cgi-bin/gitweb.cgi?p=pandora-kernel.git;a=commitdiff_plain;h=245d4b4480c20ffb50f0eddadcc6516b9017d863;ds=sidebyside KVM: x86: Fix potential divide by 0 in lapic (CVE-2013-6367) commit b963a22e6d1a266a67e9eecc88134713fd54775c upstream. 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 Signed-off-by: Andrew Honig Signed-off-by: Paolo Bonzini [bwh: Backported to 3.2: s/kvm_apic_get_reg/apic_get_reg/] Signed-off-by: Ben Hutchings --- Reading git-diff-tree failed