KVM: x86: fix for buffer overflow in handling of MSR_KVM_SYSTEM_TIME (CVE-2013-1796)
authorAndy Honig <ahonig@google.com>
Mon, 11 Mar 2013 16:34:52 +0000 (09:34 -0700)
committerMarcelo Tosatti <mtosatti@redhat.com>
Tue, 19 Mar 2013 17:17:31 +0000 (14:17 -0300)
commitc300aa64ddf57d9c5d9c898a64b36877345dd4a9
tree509c85623ff9e65c383845562db3dbce2da17531
parentc09664bb44184b3846e8c5254db4eae4b932682a
KVM: x86: fix for buffer overflow in handling of MSR_KVM_SYSTEM_TIME (CVE-2013-1796)

If the guest sets the GPA of the time_page so that the request to update the
time straddles a page then KVM will write onto an incorrect page.  The
write is done byusing kmap atomic to get a pointer to the page for the time
structure and then performing a memcpy to that page starting at an offset
that the guest controls.  Well behaved guests always provide a 32-byte aligned
address, however a malicious guest could use this to corrupt host kernel
memory.

Tested: Tested against kvmclock unit test.

Signed-off-by: Andrew Honig <ahonig@google.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
arch/x86/kvm/x86.c