CVE-2020-25085 QEMU: sdhci: out-of-bounds access issue while doing multi block SDMA

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

  Hello,

An out-of-bounds r/w access issue was found in the SDHCI Controller emulator 
of QEMU. It may occur while doing multi block SDMA, if transfer block size 
exceeds the 's->fifo_buffer[s->buf_maxsz]' size. It'd leave the current 
element pointer 's->data_count' pointing out of bounds. Leading the subsequent 
DMA r/w operation to OOB access issue. A guest user/process may use this flaw 
to crash the QEMU process resulting in DoS scenario.

Upstream patches:
-----------------
  -> https://lists.nongnu.org/archive/html/qemu-devel/2020-09/msg00733.html
  -> https://lists.nongnu.org/archive/html/qemu-devel/2020-09/msg01439.html

* This issue was reported by Sergej Schumilo, Cornelius Aschermann, Simon
  Wrner of Ruhr-University Bochum.

* 'CVE-2020-25085' 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