KVM: nVMX: Move vTPR vs. TPR Threshold consistency check into "normal" checks
Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).
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| Linux | Linux | unaffected |
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| Linux | Linux | affected |
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| Linux | Linux Kernel |
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| Linux | Linux Kernel |
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| Source | ID | Title |
|---|---|---|
Ubuntu USN |
USN-8816-1 | Linux kernel vulnerabilities |
Ubuntu USN |
USN-8816-2 | Linux kernel vulnerabilities |
Ubuntu USN |
USN-8816-3 | Linux kernel (Oracle) vulnerabilities |
Ubuntu USN |
USN-8816-4 | Linux kernel (GKE) vulnerabilities |
Ubuntu USN |
USN-8888-1 | Linux kernel (Azure) vulnerabilities |
Ubuntu USN |
USN-8888-2 | Linux kernel (Azure) vulnerabilities |
Ubuntu USN |
USN-9003-1 | Linux kernel (NVIDIA) vulnerabilities |
Ubuntu USN |
USN-9043-1 | Linux kernel (NVIDIA) vulnerabilities |
No CVSS v4.0
No CVSS v3.0
No CVSS v2
This CVE is not in the KEV list.
Exploit prediction score: < 1% (0.141% probability within 30 days)
Key SSVC decision points have not yet been added.
| Type | Values Removed | Values Added |
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| Weaknesses | CWE-20 CWE-732 |
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| Weaknesses | CWE-367 | |
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threat_severity
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threat_severity
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| Type | Values Removed | Values Added |
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| Weaknesses | CWE-20 CWE-732 |
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| Weaknesses | CWE-264 |
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| Metrics |
cvssV3_1
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| Type | Values Removed | Values Added |
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| Weaknesses | CWE-264 |
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| Description | In the Linux kernel, the following vulnerability has been resolved: KVM: nVMX: Move vTPR vs. TPR Threshold consistency check into "normal" checks Move the off-by-default consistency check for vmcs12.tpr_threshold vs. the virtual APIC vTPR into the "normal" controls checks, as waiting until KVM has loaded some amount of state is unnecessary and actively dangerous. Specifically, failure to unwind vmcs01.GUEST_CR3 to KVM's value when EPT is disabled results in KVM running L1 with an L1-controlled CR3, not with KVM's CR3! Alternatively, KVM could simply reset the MMU to force a reload of vmcs01.GUEST_CR3, but the _only_ reason the check was shoved into a "late" flow was to wait until the vmcs12 pages were retrieved. Rather than build up more crusty code, simply access vTPR using a regular guest memory access (performance isn't a concern). To circumvent the restrictions that led to KVM deferring nested_get_vmcs12_pages(), (a) use a VM-scoped API to read guest memory so that it always hits non-SMM memslots (for RSM), and (b) skip the check (since its off-by-default anyways) when the vCPU doesn't want to run, i.e. when userspace is restoring/stuffing state. If reading guest memory fails, simply skip the consistency check, as KVM's de facto ABI is that VMX instruction accesses to non-existent memory get PCI Bus Error semantics, where reads return 0xFFs. And if vTPR=0xFF, then the vTPR is guaranteed to be greater than or equal to TPR_THRESHOLD. | |
| Title | KVM: nVMX: Move vTPR vs. TPR Threshold consistency check into "normal" checks | |
| First Time appeared |
Linux
Linux linux Kernel |
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| CPEs | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | |
| Vendors & Products |
Linux
Linux linux Kernel |
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| References |
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