CVE-2018-18954 QEMU: ppc64: Out-of-bounds r/w stack access in pnv_lpc_do_eccb

[P J P <ppandit () redhat com>]

  Hello,

An OOB r/w buffer access issue was found in the PowerPC PowerNV LPC controller 
in 'pnv_lpc_do_eccb' routine. It could occur while performing a memory write 
operation. A guest user/process could use this flaw to crash the QEMU process 
resulting in DoS.

Upstream patch:
---------------
  -> https://lists.gnu.org/archive/html/qemu-devel/2018-11/msg00446.html

This issue was reported by Moguofang of Huawei.com.

Thank you.
--
Prasad J Pandit / Red Hat Product Security Team
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