Qemu: ide: ahci use-after-free vulnerability in aio port commands

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

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  Hello,

Qemu emulator built with the IDE AHCI Emulation support is vulnerable to a use 
after free(kind of) issue. It could occur after processing AHCI Native Command 
Queuing(NCQ) AIO commands.

A privileged user inside guest could use this flaw to crash the Qemu process 
instance or might potentially execute arbitrary code with privileges of the 
Qemu process on the host.

Upstream fix:
- -------------
  -> https://lists.gnu.org/archive/html/qemu-devel/2016-01/msg01184.html

Reference:
- ----------
  -> https://bugzilla.redhat.com/show_bug.cgi?id=1288532

This issue was discovered by Mr Qinghao Tang of Qihoo 360 Marvel Team.

Thank you.
- --
Prasad J Pandit / Red Hat Product Security Team
47AF CE69 3A90 54AA 9045 1053 DD13 3D32 FE5B 041F

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