CVE-2023-53254

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

cacheinfo: Fix shared_cpu_map to handle shared caches at different levels

The cacheinfo sets up the shared_cpu_map by checking whether the caches with the same index are shared between CPUs. However, this will trigger slab-out-of-bounds access if the CPUs do not have the same cache hierarchy. Another problem is the mismatched shared_cpu_map when the shared cache does not have the same index between CPUs.

CPU0 I D L3 index 0 1 2 x ^ ^ ^ ^ index 0 1 2 3 CPU1 I D L2 L3

This patch checks each cache is shared with all caches on other CPUs.

Weakness

The product reads data past the end, or before the beginning, of the intended buffer.

Affected Software

Potential Mitigations

• Assume all input is malicious. Use an “accept known good” input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does.
• When performing input validation, consider all potentially relevant properties, including length, type of input, the full range of acceptable values, missing or extra inputs, syntax, consistency across related fields, and conformance to business rules. As an example of business rule logic, “boat” may be syntactically valid because it only contains alphanumeric characters, but it is not valid if the input is only expected to contain colors such as “red” or “blue.”
• Do not rely exclusively on looking for malicious or malformed inputs. This is likely to miss at least one undesirable input, especially if the code’s environment changes. This can give attackers enough room to bypass the intended validation. However, denylists can be useful for detecting potential attacks or determining which inputs are so malformed that they should be rejected outright.
• To reduce the likelihood of introducing an out-of-bounds read, ensure that you validate and ensure correct calculations for any length argument, buffer size calculation, or offset. Be especially careful of relying on a sentinel (i.e. special character such as NUL) in untrusted inputs.

Related Attack Patterns

• https://cwe.mitre.org/data/definitions/540.html

References

• https://git.kernel.org/stable/c/198102c9103fc78d8478495971947af77edb05c1
• https://git.kernel.org/stable/c/2f588d0345d69a35e451077afed428fd057a5e34
• https://git.kernel.org/stable/c/dea49f2993f57d8a2df2cacb0bf649ef49b28879