| Name | CVE-2021-29657 |
| Description | 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. |
| Source | CVE (at NVD; CERT, LWN, oss-sec, fulldisc, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more) |
Vulnerable and fixed packages
The table below lists information on source packages.
| Source Package | Release | Version | Status |
|---|
| linux (PTS) | jessie, jessie (lts) | 3.16.84-1 | vulnerable |
| stretch (security) | 4.9.320-2 | fixed |
| stretch (lts), stretch | 4.9.320-3 | fixed |
| buster (security), buster, buster (lts) | 4.19.316-1 | fixed |
| bullseye | 5.10.223-1 | fixed |
| bullseye (security) | 5.10.226-1 | fixed |
| bookworm | 6.1.115-1 | fixed |
| bookworm (security) | 6.1.112-1 | fixed |
| trixie | 6.11.7-1 | fixed |
| sid | 6.11.9-1 | fixed |
The information below is based on the following data on fixed versions.
| Package | Type | Release | Fixed Version | Urgency | Origin | Debian Bugs |
|---|
| linux | source | jessie | (unfixed) | end-of-life | | |
| linux | source | stretch | (not affected) | | | |
| linux | source | buster | (not affected) | | | |
| linux | source | (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