KVM: x86: work around leak of uninitialized stack contents (CVE-2019-7222)

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commit 353c0956a6 upstream.

Bugzilla: 1671930

Emulation of certain instructions (VMXON, VMCLEAR, VMPTRLD, VMWRITE with
memory operand, INVEPT, INVVPID) can incorrectly inject a page fault
when passed an operand that points to an MMIO address.  The page fault
will use uninitialized kernel stack memory as the CR2 and error code.

The right behavior would be to abort the VM with a KVM_EXIT_INTERNAL_ERROR
exit to userspace; however, it is not an easy fix, so for now just
ensure that the error code and CR2 are zero.

Embargoed until Feb 7th 2019.

Reported-by: Felix Wilhelm <fwilhelm@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

...

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Paolo Bonzini 2019-01-29 18:41:16 +01:00 • committed by Ben Hutchings

parent 69c7b3bb99

commit 234a2dee1b

1 changed files with 7 additions and 0 deletions

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arch/x86/kvm/x86.c

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