Bug 2034940 (CVE-2021-28711, CVE-2021-28712, CVE-2021-28713, XSA-391) - CVE-2021-28711 CVE-2021-28712 CVE-2021-28713 xen: rogue backends can cause DoS of guests via high frequency events
Summary: CVE-2021-28711 CVE-2021-28712 CVE-2021-28713 xen: rogue backends can cause Do...
Keywords:
Status: CLOSED UPSTREAM
Alias: CVE-2021-28711, CVE-2021-28712, CVE-2021-28713, XSA-391
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
medium
medium
Target Milestone: ---
Assignee: Red Hat Product Security
QA Contact:
URL:
Whiteboard:
Depends On: 2034941 2036918 2036919 2036921 2037393 2037394
Blocks: 2034965
TreeView+ depends on / blocked
 
Reported: 2021-12-22 14:29 UTC by Guilherme de Almeida Suckevicz
Modified: 2022-01-05 19:23 UTC (History)
31 users (show)

Fixed In Version: Linux kernel 5.16-rc7
Doc Type: If docs needed, set a value
Doc Text:
A denial of service flaw for virtual machine guests in the Linux kernel's Xen hypervisor subsystem was found in the way users call some interrupts with high frequency from one of the guests. A local user could use this flaw to starve the resources resulting in a denial of service.
Clone Of:
Environment:
Last Closed: 2021-12-22 15:19:57 UTC

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Description Guilherme de Almeida Suckevicz 2021-12-22 14:29:08 UTC 
Xen offers the ability to run PV backends in regular unprivileged guests, typically referred to as "driver domains". Running PV backends in driver domains has one primary security advantage: if a driver domain gets compromised, it doesn't have the privileges to take over the system.

However, a malicious driver domain could try to attack other guests via sending events at a high frequency leading to a Denial of Service in the guest due to trying to service interrupts for elongated amounts of time.

There are three affected backends:
 * blkfront          patch 1, CVE-2021-28711
 * netfront          patch 2, CVE-2021-28712
 * hvc_xen (console) patch 3, CVE-2021-28713

Reference:
https://xenbits.xen.org/xsa/advisory-391.html
Comment 1 Guilherme de Almeida Suckevicz 2021-12-22 14:29:20 UTC 
Created xen tracking bugs for this issue:

Affects: fedora-all [bug 2034941]
Comment 2 Product Security DevOps Team 2021-12-22 15:19:55 UTC 
This CVE Bugzilla entry is for community support informational purposes only as it does not affect a package in a commercially supported Red Hat product. Refer to the dependent bugs for status of those individual community products.
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