Bug 1881401 (CVE-2020-25741)

Summary:	CVE-2020-25741 QEMU: fdc: null pointer dereference during r/w data transfer
Product:	[Other] Security Response	Reporter:	Prasad Pandit <ppandit>
Component:	vulnerability	Assignee:	Red Hat Product Security <security-response-team>
Status:	CLOSED WONTFIX	QA Contact:
Severity:	low	Docs Contact:
Priority:	low
Version:	unspecified	CC:	ailan, berrange, cfergeau, drjones, imammedo, itamar, jen, jferlan, jforbes, jjoyce, jmaloy, jschluet, knoel, lhh, lpeer, m.a.young, mburns, mkenneth, mrezanin, mst, ondrejj, pbonzini, philmd, qinwang, ribarry, rjones, robinlee.sysu, sclewis, slinaber, virt-maint, virt-maint, vkuznets, xen-maint
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:	QEMU 5.1.1	Doc Type:	If docs needed, set a value
Doc Text:	A NULL pointer dereference flaw was found in the Floppy disk emulator of QEMU. This issue occurs while transferring data via the fdctrl_read_data() and fdctrl_write_data() routines if the current drive has a null block pointer. This flaw allows a guest user to crash the QEMU process on the host, resulting in a denial of service.	Story Points:	---
Clone Of:		Environment:
Last Closed:	2021-12-15 12:06:28 UTC	Type:	---
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:
Bug Depends On:	1881402, 1881403, 1881404, 1881405, 1881406, 1881407, 1881408, 1910673
Bug Blocks:	1850259

Description Prasad Pandit 2020-09-22 11:04:22 UTC

A null pointer dereference issue was found in the Floppy disk emulator of QEMU. It could occur while transferring data via fdctrl_read_data(), fdctrl_write_data() routines, if current drive has a null block pointer. A guest may use this flaw to crash the QEMU process on the host resulting in DoS scenario.

Upstream patch:
---------------
  -> https://lists.nongnu.org/archive/html/qemu-devel/2020-09/msg07779.html

Comment 1 Prasad Pandit 2020-09-22 11:04:37 UTC

Acknowledgments:

Name: Sergej Schumilo (Ruhr-University Bochum), Cornelius Aschermann (Ruhr-University Bochum), Simon Wrner (Ruhr-University Bochum)

Comment 2 Prasad Pandit 2020-09-22 11:04:45 UTC

External References:

https://www.openwall.com/lists/oss-security/2020/09/29/1
https://ruhr-uni-bochum.sciebo.de/s/NNWP2GfwzYKeKwE?path=%2Ffdc_nullptr1

Comment 3 Prasad Pandit 2020-09-22 11:05:34 UTC

Created qemu tracking bugs for this issue:

Affects: fedora-all [bug 1881402]


Created xen tracking bugs for this issue:

Affects: fedora-all [bug 1881403]