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.
The product checks the state of a resource before using that resource, but the resource's state can change between the check and the use in a way that invalidates the results of the check. This can cause the product to perform invalid actions when the resource is in an unexpected state.
| Link | Tags |
|---|---|
| http://packetstormsecurity.com/files/163324/KVM-nested_svm_vmrun-Double-Fetch.html | vdb entry third party advisory |
| https://bugs.chromium.org/p/project-zero/issues/detail?id=2177 | mailing list patch exploit third party advisory |
| https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=a58d9166a756a0f4a6618e4f593232593d6df134 | third party advisory patch |
| https://cdn.kernel.org/pub/linux/kernel/v5.x/ChangeLog-5.11.12 | exploit patch vendor advisory |
| https://security.netapp.com/advisory/ntap-20210902-0008/ | third party advisory |