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CVE-2025-21991

x86/microcode/AMD: Fix out-of-bounds on systems with CPU-less NUMA nodes

HIGH 7.8

At a glance

Source
NVD
EPSS
EPSS 0.22 % · percentile 13 ()
State
PUBLISHED
Published
Updated
Assigner
Linux
NVD status
Modified

Description

In the Linux kernel, the following vulnerability has been resolved: x86/microcode/AMD: Fix out-of-bounds on systems with CPU-less NUMA nodes Currently, load_microcode_amd() iterates over all NUMA nodes, retrieves their CPU masks and unconditionally accesses per-CPU data for the first CPU of each mask. According to Documentation/admin-guide/mm/numaperf.rst: "Some memory may share the same node as a CPU, and others are provided as memory only nodes." Therefore, some node CPU masks may be empty and wouldn't have a "first CPU". On a machine with far memory (and therefore CPU-less NUMA nodes): - cpumask_of_node(nid) is 0 - cpumask_first(0) is CONFIG_NR_CPUS - cpu_data(CONFIG_NR_CPUS) accesses the cpu_info per-CPU array at an index that is 1 out of bounds This does not have any security implications since flashing microcode is a privileged operation but I believe this has reliability implications by potentially corrupting memory while flashing a microcode update. When booting with CONFIG_UBSAN_BOUNDS=y on an AMD machine that flashes a microcode update. I get the following splat: UBSAN: array-index-out-of-bounds in arch/x86/kernel/cpu/microcode/amd.c:X:Y index 512 is out of range for type 'unsigned long[512]' [...] Call Trace: dump_stack __ubsan_handle_out_of_bounds load_microcode_amd request_microcode_amd reload_store kernfs_fop_write_iter vfs_write ksys_write do_syscall_64 entry_SYSCALL_64_after_hwframe Change the loop to go over only NUMA nodes which have CPUs before determining whether the first CPU on the respective node needs microcode update. [ bp: Massage commit message, fix typo. ]

Weaknesses (CWE)

  • CWE-129 — Improper Validation of Array Index

References

Scores

VersionScoreVectorScored by
CVSS 3.1HIGH 7.8CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:HCISA-ADP
CVSS 3.1HIGH 7.8CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:HNVD · nvd@nist.gov (Primary)
CVSS 3.1HIGH 7.8CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:HNVD · 134c704f-9b21-4f2e-91b3-4a467353bcc0 (Secondary)

European references

CERT-FR advisories

Affected configurations (NVD CPE)

Affected products

ProductVersions
Linux · Linuxaffected 979e197968a1e8f09bf0d706801dba4432f85ab3 < d509c4731090ebd9bbdb72c70a2d70003ae81f4f ; affected 44a44b57e88f311c1415be1f567c50050913c149 < 985a536e04bbfffb1770df43c6470f635a6b1073 ; affected be2710deaed3ab1402379a2ede30a3754fe6767a < 18b5d857c6496b78ead2fd10001b81ae32d30cac ; affected d576547f489c935b9897d4acf8beee3325dea8a5 < ec52240622c4d218d0240079b7c1d3ec2328a9f4 ; affected 7ff6edf4fef38ab404ee7861f257e28eaaeed35f < e686349cc19e800dac8971929089ba5ff59abfb0 ; affected 7ff6edf4fef38ab404ee7861f257e28eaaeed35f < 488ffc0cac38f203979f83634236ee53251ce593
Linux · Linuxaffected 6.3 ; unaffected 0 < 6.3 ; unaffected 5.4.292 ≤ 5.4.* ; unaffected 5.10.236 ≤ 5.10.* ; unaffected 5.15.180 ≤ 5.15.* ; unaffected 6.1.132 ≤ 6.1.*

Sources

SourceLicence
CVE List (CVEProject cvelistV5)CVE Program Terms of Use
EPSS (FIRST.org)FIRST — attribution requested
ENISA EUVDENISA — reproduction authorised, source acknowledged
CERT-FR (ANSSI)Licence Ouverte / Etalab 2.0
NVD (NIST) via fkie-cad/nvd-json-data-feedsPublic domain — this product uses data from the NVD API but is not endorsed or certified by the NVD