CVE-2021-29657: Use After Free
First published: Thu Jul 22 2021(Updated: )
arch/x86/kvm/svm/nested.c in the Linux kernel before 5.11.12 has a use-after-free in which an AMD KVM guest can bypass access control on host OS MSRs when there are nested guests, aka CID-a58d9166a756. This occurs because of a TOCTOU race condition associated with a VMCB12 double fetch in nested_svm_vmrun.
Credit: cve@mitre.org cve@mitre.org
| Affected Software | Affected Version | How to fix |
|---|---|---|
| Linux Linux kernel | >=5.10<5.10.28 | |
| Linux Linux kernel | >=5.11<5.11.12 | |
| debian/linux | 5.10.223-1 5.10.226-1 6.1.115-1 6.1.119-1 6.12.6-1 6.12.8-1 |
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Reference Links
- http://packetstormsecurity.com/files/163324/KVM-nested_svm_vmrun-Double-Fetch.html
- https://bugs.chromium.org/p/project-zero/issues/detail?id=2177
- https://cdn.kernel.org/pub/linux/kernel/v5.x/ChangeLog-5.11.12
- https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=a58d9166a756a0f4a6618e4f593232593d6df134
- https://security.netapp.com/advisory/ntap-20210902-0008/
- https://launchpad.net/bugs/cve/CVE-2021-29657
- https://git.kernel.org/linus/a58d9166a756a0f4a6618e4f593232593d6df134
- https://googleprojectzero.blogspot.com/2021/06/an-epyc-escape-case-study-of-kvm.html
- https://security-tracker.debian.org/tracker/CVE-2021-29657
- https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-29657
- https://nvd.nist.gov/vuln/detail/CVE-2021-29657
- https://ubuntu.com/security/CVE-2021-29657
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