CVE-2015-7549 Qemu: pci: msi-x: null pointer dereference issue

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

  Hello,

Qemu emulator built with the PCI MSI-X support is vulnerable to null pointer 
dereference issue. It occurs when the controller attempts to write to the 
pending bit array(PBA) memory region. Because the MSI-X MMIO support did not 
define the .write method.

A privileges used inside guest could use this flaw to crash the Qemu process 
resulting in DoS issue.

Upstream fix:
-------------
  -> http://git.qemu.org/?p=qemu.git;a=commit;h=43b11a91dd861a946b231b89b754285

CVE-2015-7549 has been assigned to this issue by Red Hat Inc.

This issue was reported by Qinghao Tang of QIHU 360 Marvel Team.

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