KVM: x86: Emulator fixes for eip canonical checks on near branches

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commit 234f3ce485 upstream.

Before changing rip (during jmp, call, ret, etc.) the target should be asserted
to be canonical one, as real CPUs do.  During sysret, both target rsp and rip
should be canonical. If any of these values is noncanonical, a #GP exception
should occur.  The exception to this rule are syscall and sysenter instructions
in which the assigned rip is checked during the assignment to the relevant
MSRs.

This patch fixes the emulator to behave as real CPUs do for near branches.
Far branches are handled by the next patch.

This fixes CVE-2014-3647.

Signed-off-by: Nadav Amit <namit@cs.technion.ac.il>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

...

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Nadav Amit 2014-09-18 22:39:38 +03:00 • committed by Greg Kroah-Hartman

parent 9cbba3890c

commit 6dae4910ca

1 changed files with 54 additions and 24 deletions

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arch/x86/kvm/emulate.c

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