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. ]
References
Configurations
Configuration 1 (hide)
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History
10 Apr 2025, 13:24
Type | Values Removed | Values Added |
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CVSS |
v2 : v3 : |
v2 : unknown
v3 : 7.8 |
CWE | CWE-129 | |
First Time |
Linux linux Kernel
Linux |
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References | () https://git.kernel.org/stable/c/18b5d857c6496b78ead2fd10001b81ae32d30cac - Patch | |
References | () https://git.kernel.org/stable/c/488ffc0cac38f203979f83634236ee53251ce593 - Patch | |
References | () https://git.kernel.org/stable/c/5ac295dfccb5b015493f86694fa13a0dde4d3665 - Patch | |
References | () https://git.kernel.org/stable/c/985a536e04bbfffb1770df43c6470f635a6b1073 - Patch | |
References | () https://git.kernel.org/stable/c/d509c4731090ebd9bbdb72c70a2d70003ae81f4f - Patch | |
References | () https://git.kernel.org/stable/c/e3e89178a9f4a80092578af3ff3c8478f9187d59 - Patch | |
References | () https://git.kernel.org/stable/c/e686349cc19e800dac8971929089ba5ff59abfb0 - Patch | |
References | () https://git.kernel.org/stable/c/ec52240622c4d218d0240079b7c1d3ec2328a9f4 - Patch | |
CPE | cpe:2.3:o:linux:linux_kernel:6.14:rc5:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:6.14:rc2:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:6.14:rc1:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:6.14:rc3:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:6.14:rc4:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:6.14:rc6:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* |
10 Apr 2025, 13:15
Type | Values Removed | Values Added |
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Summary |
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References |
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02 Apr 2025, 13:15
Type | Values Removed | Values Added |
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New CVE |
Information
Published : 2025-04-02 13:15
Updated : 2025-04-10 13:24
NVD link : CVE-2025-21991
Mitre link : CVE-2025-21991
CVE.ORG link : CVE-2025-21991
JSON object : View
Products Affected
linux
- linux_kernel
CWE
CWE-129
Improper Validation of Array Index