Skip to content
CVE PROGRAM SOURCE RECORD7.8 High

CVE-2025-21991

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

Read JSON ↗CVE.org ↗
Status
Published
Published
Updated
Assigning organization
Linux

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. ]

Affected products

Version statuses are supplied by the assigning organization. Consult the original record for detailed ranges and platform conditions.

Linux Linux

Default version status: unaffected

  • 979e197968a1e8f09bf0d706801dba4432f85ab3 to < d509c4731090ebd9bbdb72c70a2d70003ae81f4faffected
  • 44a44b57e88f311c1415be1f567c50050913c149 to < 985a536e04bbfffb1770df43c6470f635a6b1073affected
  • be2710deaed3ab1402379a2ede30a3754fe6767a to < 18b5d857c6496b78ead2fd10001b81ae32d30cacaffected
  • d576547f489c935b9897d4acf8beee3325dea8a5 to < ec52240622c4d218d0240079b7c1d3ec2328a9f4affected
  • 7ff6edf4fef38ab404ee7861f257e28eaaeed35f to < e686349cc19e800dac8971929089ba5ff59abfb0affected
  • 7ff6edf4fef38ab404ee7861f257e28eaaeed35f to < 488ffc0cac38f203979f83634236ee53251ce593affected
  • 7ff6edf4fef38ab404ee7861f257e28eaaeed35f to < 5ac295dfccb5b015493f86694fa13a0dde4d3665affected
  • 7ff6edf4fef38ab404ee7861f257e28eaaeed35f to < e3e89178a9f4a80092578af3ff3c8478f9187d59affected
  • d6353e2fc12c5b8f00f86efa30ed73d2da2f77beaffected
  • 1b1e0eb1d2971a686b9f7bdc146115bcefcbb960affected
  • eaf5dea1eb8c2928554b3ca717575cbe232b843caffected
  • 5.4.235 to < 5.4.292affected
  • 5.10.173 to < 5.10.236affected
  • 5.15.99 to < 5.15.180affected
  • 6.1.16 to < 6.1.132affected
  • 4.14.308 to < 4.15affected
  • 4.19.276 to < 4.20affected
  • 6.2.3 to < 6.3affected

Linux Linux

Default version status: affected

  • 6.3affected
  • 0 to < 6.3unaffected
  • 5.4.292 to ≤ 5.4.*unaffected
  • 5.10.236 to ≤ 5.10.*unaffected
  • 5.15.180 to ≤ 5.15.*unaffected
  • 6.1.132 to ≤ 6.1.*unaffected
  • 6.6.84 to ≤ 6.6.*unaffected
  • 6.12.20 to ≤ 6.12.*unaffected
  • 6.13.8 to ≤ 6.13.*unaffected
  • 6.14 to ≤ *unaffected

References