SB2021072294 - Use-after-free in Linux kernel AMD KVM
Published: July 22, 2021 Updated: July 25, 2022
Security Bulletin ID
SB2021072294
CSH Severity
Medium
Patch available
YES
Number of vulnerabilities
1
Exploitation vector
Remote access
Highest impact
Code execution
Breakdown by Severity
- Low
- Medium
- High
- Critical
Description
This security bulletin contains information about 1 vulnerability.
1) Use-after-free (CVE-ID: CVE-2021-29657)
CWE-ID: CWE-416 - Use After Free
CVSSv4: 7.7 [CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N]
The vulnerability allows a remote user to compromise vulnerable system.
The vulnerability exists due to a use-after-free error in arch/x86/kvm/svm/nested.c. An AMD KVM guest can bypass access control on host OS MSRs when there are nested guests and execute arbitrary code on the hypervisor.
Remediation
Install update from vendor's website.
References
- https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=a58d9166a756a0f4a6618e4f593232593d6df134
- https://bugs.chromium.org/p/project-zero/issues/detail?id=2177
- https://cdn.kernel.org/pub/linux/kernel/v5.x/ChangeLog-5.11.12
- http://packetstormsecurity.com/files/163324/KVM-nested_svm_vmrun-Double-Fetch.html
- https://security.netapp.com/advisory/ntap-20210902-0008/