CVE-2017-5987 Qemu: sd: infinite loop issue in multi block transfers

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

  Hello,

Quick emulator(Qemu) built with the SDHCI device emulation support is 
vulnerable to an infinite loop issue. It could occur while doing a multi block 
SDMA transfer via 'sdhci_sdma_transfer_multi_blocks' routine.

A privileged user inside guest could use this flaw to crash the Qemu process 
resulting in DoS.

Upstream patch:
---------------
  -> https://lists.gnu.org/archive/html/qemu-devel/2017-02/msg02776.html

Reference:
----------
  -> https://bugzilla.redhat.com/show_bug.cgi?id=1421995

This issue was independently reported by Mr Jiang Xin of Huawei.com and 
Wjjzhang of Tencent.com.

'CVE-2017-5987' assigned via -> https://cveform.mitre.org/

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