Bug 1856441 (CVE-2020-15852) - CVE-2020-15852 xen: Linux ioperm bitmap context switching issues
Summary: CVE-2020-15852 xen: Linux ioperm bitmap context switching issues
Keywords:
Status: CLOSED NOTABUG
Alias: CVE-2020-15852
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: 1857794
Blocks: 1856442
TreeView+ depends on / blocked
 
Reported: 2020-07-13 16:26 UTC by Guilherme de Almeida Suckevicz
Modified: 2021-02-16 19:41 UTC (History)
49 users (show)

Fixed In Version:
Doc Type: If docs needed, set a value
Doc Text:
A flaw was found in the Linux kernel, in the way IOPL and IOPERM system calls were handled during context switches in x86 PV guests. This flaw allows a local guest user to escalate their privileges to the guest. The highest threat from this vulnerability is to data confidentiality and integrity as well as system availability.
Clone Of:
Environment:
Last Closed: 2020-07-16 19:27:36 UTC
Embargoed:

Attachments (Terms of Use)

Description Guilherme de Almeida Suckevicz 2020-07-13 16:26:09 UTC 
Linux 5.5 overhauled the internal state handling for the iopl() and ioperm() system calls.  Unfortunately, one aspect on context switch wasn't wired up correctly for the Xen PVOps case.
Comment 1 Mauro Matteo Cascella 2020-07-16 13:59:06 UTC 
Acknowledgments:

Name: the Xen project
Comment 2 Mauro Matteo Cascella 2020-07-16 14:05:50 UTC 
External References:

https://xenbits.xen.org/xsa/advisory-329.html
Comment 3 Mauro Matteo Cascella 2020-07-16 14:53:39 UTC 
Statement:

The vulnerability can only be exploited in domains which have been granted access to IO ports by Xen. This is typically only the hardware domain, and PV guests configured with PCI passthrough. x86 HVM/PVH guests are not affected by this flaw.
Comment 4 Mauro Matteo Cascella 2020-07-16 15:11:30 UTC 
Created kernel tracking bugs for this issue:

Affects: fedora-all [bug 1857794]
Comment 9 Justin M. Forbes 2020-10-08 19:12:55 UTC 
This was fixed for Fedora with the 5.7.10 stable kernel updates.
Note You need to log in before you can comment on or make changes to this bug.