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CVE-2023-53496

MEDIUMCVSS 5.5/10EPSS 0.13%

Last modified

CVE-2023-53496 is a medium-severity vulnerability rated 5.5/10 on the CVSS scale. In the Linux kernel, the following vulnerability has been resolved: x86/platform/uv: Use alternate source for socket to node data The UV code attempts to build a set of tables to allow it to do bidirectional socket<=>node lookups. But when nr_cpus is set to a smaller number than actually present, the cpu_to_node() mapping information for unused CPUs is not available to build_socket_tables(). This results in skipping some nodes or sockets when creating the tables and leaving some -1's for later code to trip. over, causing oopses. The problem is that the socket<=>node lookups are created by doing a loop over all CPUs, then looking up the CPU's APICID and socket. EPSS estimates a 0.13% chance of exploitation in the next 30 days.

Description

In the Linux kernel, the following vulnerability has been resolved: x86/platform/uv: Use alternate source for socket to node data The UV code attempts to build a set of tables to allow it to do bidirectional socket<=>node lookups. But when nr_cpus is set to a smaller number than actually present, the cpu_to_node() mapping information for unused CPUs is not available to build_socket_tables(). This results in skipping some nodes or sockets when creating the tables and leaving some -1's for later code to trip. over, causing oopses. The problem is that the socket<=>node lookups are created by doing a loop over all CPUs, then looking up the CPU's APICID and socket. But if a CPU is not present, there is no way to start this lookup. Instead of looping over all CPUs, take CPUs out of the equation entirely. Loop over all APICIDs which are mapped to a valid NUMA node. Then just extract the socket-id from the APICID. This avoid tripping over disabled CPUs.

Metrics

CVSS 3.1
5.5/10

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

EPSS Probability
0.13%

2.5th percentile

Probability of exploitation in the next 30 days. Learn more

Affected Software

VendorProductVersionsUpdate
LinuxLinux Kernel>= 6.5, < 6.5.5—
LinuxLinux Kernel6.6Rc1

References

Timeline

Published
Last Modified
Status
Analyzed

Frequently Asked Questions

What is CVE-2023-53496?
In the Linux kernel, the following vulnerability has been resolved: x86/platform/uv: Use alternate source for socket to node data The UV code attempts to build a set of tables to allow it to do bidirectional socket<=>node lookups. But when nr_cpus is set to a smaller number than actually present, the cpu_to_node() mapping information for unused CPUs is not available to build_socket_tables(). This results in skipping some nodes or sockets when creating the tables and leaving some -1's for later code to trip. over, causing oopses. The problem is that the socket<=>node lookups are created by doing a loop over all CPUs, then looking up the CPU's APICID and socket. But if a CPU is not present, there is no way to start this lookup. Instead of looping over all CPUs, take CPUs out of the equation entirely. Loop over all APICIDs which are mapped to a valid NUMA node. Then just extract the socket-id from the APICID. This avoid tripping over disabled CPUs.
How severe is CVE-2023-53496?
CVE-2023-53496 has a CVSS score of 5.5/10 (MEDIUM severity). The EPSS model estimates a 0.13% probability of exploitation in the next 30 days.
How do I fix CVE-2023-53496?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2023-53496?

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Source: NVD / NIST