CVE request - kvm: cat /dev/port in the guest can cause host DoS

[Eugene Teo <eugeneteo () kernel sg>]

The problem is pit_state->channels[] has 3 elements, and pit_ioport_read 
uses "addr" as index to pit_get_count, so inb(0x43) reads (and 
potentially writes) into other data of kvm_kpit_state.

PIT control word (address 0x43) is write-only, reads are undefined.

Triggering this can cause a general protection fault on the host.

https://bugzilla.redhat.com/show_bug.cgi?id=560887
http://www.mail-archive.com/kvm () vger kernel org/msg28002.html

Thanks, Eugene
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Eugene Teo / Red Hat Security Response Team