CVE-2021-29657

NameCVE-2021-29657
Descriptionarch/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.
SourceCVE (at NVD; CERT, LWN, oss-sec, fulldisc, bugtraq, EDB, Metasploit, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, Mageia, GitHub code/issues, web search, more)

Vulnerable and fixed packages

The table below lists information on source packages.

Source PackageReleaseVersionStatus
linux (PTS)stretch4.9.228-1fixed
stretch (security)4.9.272-2fixed
buster4.19.194-1fixed
buster (security)4.19.194-3fixed
bullseye5.10.46-2fixed
sid5.10.46-3fixed

The information below is based on the following data on fixed versions.

PackageTypeReleaseFixed VersionUrgencyOriginDebian Bugs
linuxsourcestretch(not affected)
linuxsourcebuster(not affected)
linuxsource(unstable)5.10.28-1

Notes

[buster] - linux <not-affected> (Vulnerable code introduced later)
[stretch] - linux <not-affected> (Vulnerable code introduced later)
https://git.kernel.org/linus/a58d9166a756a0f4a6618e4f593232593d6df134
https://googleprojectzero.blogspot.com/2021/06/an-epyc-escape-case-study-of-kvm.html

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