bpf: Fix BPF_F_CPU validation for sparse CPU IDs

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Summary

CVECVE-2026-98150
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-09-25 11:17:46 UTC
Updated2026-09-25 15:18:06 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: bpf: Fix BPF_F_CPU validation for sparse CPU IDs BPF_F_CPU stores the target CPU ID in the upper 32 bits of the map operation flags. bpf_map_check_op_flags() currently compares that ID with num_possible_cpus(), which is the number of possible CPUs rather than a bound on CPU IDs. On an arm64 QEMU guest with a CPU device-tree hole, the possible CPU mask was 0,2-3. A userspace program using raw bpf() syscalls creates a BPF_MAP_TYPE_PERCPU_ARRAY and performs update and lookup operations for each CPU by setting BPF_F_CPU and the CPU ID in the flags. With the old check, CPU 1 is incorrectly accepted while valid CPU 3 is rejected with -ERANGE. The CPU 1 update then reaches the per-CPU map access path and triggers: Unable to handle kernel paging request at virtual address ... pc : __pi_memcpy_generic+0x5c/0x22c lr : bpf_percpu_array_update+0x2dc/0x2e8 Call trace: __pi_memcpy_generic bpf_map_update_value map_update_elem __sys_bpf Check the CPU ID against nr_cpu_ids and cpu_possible() instead. This rejects CPU IDs outside the valid range and CPUs absent from the possible mask, while allowing valid sparse CPU IDs.

Risk And Classification

Primary CVSS: v3.1 7 HIGH from 416baaa9-dc9f-4396-8d5f-8c081fb06d67

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

VersionSourceTypeScoreSeverityVector
3.1416baaa9-dc9f-4396-8d5f-8c081fb06d67Secondary7HIGHCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
3.1CNADECLARED7HIGHCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H

CVSS v3.1 Breakdown

Attack Vector
Local
Attack Complexity
High
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

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

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected 2b421662c7887a0649fe409155a1f101562d0fa9 bdc5941f6eeef90b76a07fd8ca38ac1933ba2195 git Not specified
CNA Linux Linux affected 2b421662c7887a0649fe409155a1f101562d0fa9 ed54bf564ac52699cf4def3d0c2125d493e756f9 git Not specified
CNA Linux Linux affected 7.0 Not specified
CNA Linux Linux unaffected 7.0 semver Not specified
CNA Linux Linux unaffected 7.2.7 7.2.* semver Not specified
CNA Linux Linux unaffected 7.3-rc2 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/bdc5941f6eeef90b76a07fd8ca38ac1933ba2195 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/ed54bf564ac52699cf4def3d0c2125d493e756f9 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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