bpf: Cancel special fields on map value recycle

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-74314
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-08-15 06:22:31 UTC
Updated2026-08-17 06:19:25 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: bpf: Cancel special fields on map value recycle Map update and delete paths currently call bpf_obj_free_fields() when a value is being replaced or recycled. That makes field destruction depend on the context of the update/delete operation. For tracing programs this can include NMI context, where referenced kptr destructors, uptr unpinning, and graph root destruction are not generally safe. Introduce bpf_obj_cancel_fields() for the reusable-value path. It only performs NMI-safe cleanup for timer, workqueue, and task_work fields. Fields that need full destruction are left attached to the recycled value and are destroyed by the final cleanup path instead. Switch array and hashtab update/delete/recycle paths to this cancel helper. Keep bpf_obj_free_fields() for final map destruction and for bpf_mem_alloc destructors. Preallocated hashtabs do not have allocator destructors, so teardown continues to walk the normal and extra elements and fully destroy their fields. This deliberately relaxes the eager-free semantics of map update/delete for special fields. Programs that relied on a recycled map slot becoming empty immediately after update/delete were relying on behavior that cannot be implemented safely from every BPF execution context without offloading arbitrary destructors. There is a chance this change breaks programs making assumptions regarding the eager freeing of fields. If so, we can relax semantics to cancellation only when irqs_disabled() is true in the future. However, theoretically, map values that get reused eagerly already have weaker guarantees as parallel users can recreate freed fields before the new element becomes visible again.

Risk And Classification

Primary CVSS: v3.1 7.8 HIGH from 416baaa9-dc9f-4396-8d5f-8c081fb06d67

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

EPSS: 0.001290000 probability, percentile 0.029640000 (date 2026-08-17)

VersionSourceTypeScoreSeverityVector
3.1416baaa9-dc9f-4396-8d5f-8c081fb06d67Secondary7.8HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
3.1CNADECLARED7.8HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

CVSS v3.1 Breakdown

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

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

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected 14a324f6a67ef6a53e04362a70160a47eb8afffa 9ea734e2cc0143d7429ab7dc0b20c85e5836183c git Not specified
CNA Linux Linux affected 14a324f6a67ef6a53e04362a70160a47eb8afffa a3a81d247651218e47153f2d2afd7aee236726fd git Not specified
CNA Linux Linux affected f0462d38589422bc9e27fd3c6343dfeb6b3db2f9 git Not specified
CNA Linux Linux affected 5.18.18 5.19 semver Not specified
CNA Linux Linux affected 5.19 Not specified
CNA Linux Linux unaffected 5.19 semver Not specified
CNA Linux Linux unaffected 7.1.5 7.1.* semver Not specified
CNA Linux Linux unaffected 7.2 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/9ea734e2cc0143d7429ab7dc0b20c85e5836183c 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/a3a81d247651218e47153f2d2afd7aee236726fd 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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