CVE-2020-8834 Detail

Current Description

KVM in the Linux kernel on Power8 processors has a conflicting use of HSTATE_HOST_R1 to store r1 state in kvmppc_hv_entry plus in kvmppc_{save,restore}_tm, leading to a stack corruption. Because of this, an attacker with the ability run code in kernel space of a guest VM can cause the host kernel to panic. There were two commits that, according to the reporter, introduced the vulnerability: f024ee098476 ("KVM: PPC: Book3S HV: Pull out TM state save/restore into separate procedures") 87a11bb6a7f7 ("KVM: PPC: Book3S HV: Work around XER[SO] bug in fake suspend mode") The former landed in 4.8, the latter in 4.17. This was fixed without realizing the impact in 4.18 with the following three commits, though it's believed the first is the only strictly necessary commit: 6f597c6b63b6 ("KVM: PPC: Book3S PR: Add guest MSR parameter for kvmppc_save_tm()/kvmppc_restore_tm()") 7b0e827c6970 ("KVM: PPC: Book3S HV: Factor fake-suspend handling out of kvmppc_save/restore_tm") 009c872a8bc4 ("KVM: PPC: Book3S PR: Move kvmppc_save_tm/kvmppc_restore_tm to separate file")


View Analysis Description

Severity



CVSS 3.x Severity and Metrics:

NIST CVSS score matches with CNA score
CNA:  Canonical Ltd.
Base Score:  6.5 MEDIUM
Vector:  CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:N/I:N/A:H


NVD Analysts use publicly available information to associate vector strings and CVSS scores. We also display any CVSS information provided within the CVE List from the CNA.

Note: The NVD and the CNA have provided the same score. When this occurs only the CNA information is displayed, but the Acceptance Level icon for the CNA is given a checkmark to signify NVD concurrence.

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Hyperlink Resource
http://lists.opensuse.org/opensuse-security-announce/2020-04/msg00035.html
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1867717 Exploit  Third Party Advisory 
https://usn.ubuntu.com/4318-1/ Third Party Advisory 
https://usn.ubuntu.com/usn/usn-4318-1 Third Party Advisory 
https://www.openwall.com/lists/oss-security/2020/04/06/2 Mailing List  Third Party Advisory 

Weakness Enumeration

CWE-ID CWE Name Source
CWE-362 Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition') cwe source acceptance level NIST  
CWE-368 Context Switching Race Condition Reference acceptance level Canonical Ltd.  

Known Affected Software Configurations Switch to CPE 2.2

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Change History

5 change records found show changes

Quick Info

CVE Dictionary Entry:
CVE-2020-8834
NVD Published Date:
04/09/2020
NVD Last Modified:
04/23/2020
Source:
Canonical Ltd.