https://github.com/torvalds/linux
Revision b963a22e6d1a266a67e9eecc88134713fd54775c authored by Andy Honig on 19 November 2013, 22:12:18 UTC, committed by Paolo Bonzini on 12 December 2013, 21:39:45 UTC
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 <ahonig@google.com>
Cc: stable@vger.kernel.org
Signed-off-by: Andrew Honig <ahonig@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
1 parent 338c7db
History
Tip revision: b963a22e6d1a266a67e9eecc88134713fd54775c authored by Andy Honig on 19 November 2013, 22:12:18 UTC
KVM: x86: Fix potential divide by 0 in lapic (CVE-2013-6367)
Tip revision: b963a22
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