CVE-2020-25625 QEMU: usb: hcd-ohci: infinite loop issue while processing transfer descriptors

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

  Hello,

An infinite loop issue was found in the USB OHCI controller emulator of QEMU. 
It could occur while servicing OHCI isochronous transfer descriptors (TD) in 
ohci_service_iso_td routine, as it retires a TD if it has passed its time 
frame. While doing so it does not check if the TD was already processed ones 
and holds an error code in TD_CC. It may happen if the TD list has a loop.

A guest user/process may use this flaw to consume cpu cycles on the host 
resulting in a DoS scenario.

Upstream patch:
---------------
  -> https://lists.nongnu.org/archive/html/qemu-devel/2020-09/msg05905.html

'CVE-2020-25625' assigned via https://cveform.mitre.org/

Thank you.
--
Prasad J Pandit / Red Hat Product Security Team
8685 545E B54C 486B C6EB 271E E285 8B5A F050 DE8D