CVE-2021-47262

/// Technical description

In the Linux kernel, the following vulnerability has been resolved:

KVM: x86: Ensure liveliness of nested VM-Enter fail tracepoint message

Use the __string() machinery provided by the tracing subystem to make a

copy of the string literals consumed by the "nested VM-Enter failed"

tracepoint. A complete copy is necessary to ensure that the tracepoint

can't outlive the data/memory it consumes and deference stale memory.

Because the tracepoint itself is defined by kvm, if kvm-intel and/or

kvm-amd are built as modules, the memory holding the string literals

defined by the vendor modules will be freed when the module is unloaded,

whereas the tracepoint and its data in the ring buffer will live until

kvm is unloaded (or "indefinitely" if kvm is built-in).

This bug has existed since the tracepoint was added, but was recently

exposed by a new check in tracing to detect exactly this type of bug.

fmt: '%s%s

' current_buffer: ' vmx_dirty_log_t-140127 [003] .... kvm_nested_vmenter_faile

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References