CVE-2023-3640

A possible unauthorized memory access flaw was found in the Linux kernels cpu_entry_area mapping of X86 CPU data to memory, where a user may guess the location of exception stacks or other important data. Based on the previous CVE-2023-0597, the Randomize per-cpu entry area feature was implemented in /arch/x86/mm/cpu_entry_area.c, which works through the init_cea_offsets() function when KASLR is enabled. However, despite this feature, there is still a risk of per-cpu entry area leaks. This issue could allow a local user to gain access to some important data with memory in an expected location and potentially escalate their privileges on the system.

Weakness

Covert timing channels convey information by modulating some aspect of system behavior over time, so that the program receiving the information can observe system behavior and infer protected information.

Affected Software

Extended Description

In some instances, knowing when data is transmitted between parties can provide a malicious user with privileged information. Also, externally monitoring the timing of operations can potentially reveal sensitive data. For example, a cryptographic operation can expose its internal state if the time it takes to perform the operation varies, based on the state. Covert channels are frequently classified as either storage or timing channels. Some examples of covert timing channels are the system’s paging rate, the time a certain transaction requires to execute, and the time it takes to gain access to a shared bus.

Potential Mitigations

Related Attack Patterns

• https://cwe.mitre.org/data/definitions/462.html

References

• https://access.redhat.com/errata/RHSA-2023:6583
• https://access.redhat.com/security/cve/CVE-2023-3640
• https://bugzilla.redhat.com/show_bug.cgi?id=2217523
• https://access.redhat.com/security/cve/CVE-2023-3640
• https://bugzilla.redhat.com/show_bug.cgi?id=2217523