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bpf: Cancel special fields on map value recycle

Type: advisorySource: Official CVE List1 source record

In 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 canc

Announced Source revision 1
Original source ↗

CVE-2026-74314

Primary source · Revision 1

Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.

Security context

Source reference: cve:CVE-2026-74314

Linux

Source reference: /containers/cna/affected/0/product

Affected versions
Not stated in this record
Fixed versions
Not stated in this record
Prerequisites
Not stated in this record

Linux

Source reference: /containers/cna/affected/1/product

Affected versions
Not stated in this record
Fixed versions
Not stated in this record
Prerequisites
Not stated in this record

Structured affected-version data

Original package identities and version rules from this source.

[
  {
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "vendor": "Linux",
    "product": "Linux",
    "versions": [
      {
        "status": "affected",
        "version": "14a324f6a67ef6a53e04362a70160a47eb8afffa",
        "lessThan": "9ea734e2cc0143d7429ab7dc0b20c85e5836183c",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "14a324f6a67ef6a53e04362a70160a47eb8afffa",
        "lessThan": "a3a81d247651218e47153f2d2afd7aee236726fd",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "f0462d38589422bc9e27fd3c6343dfeb6b3db2f9",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "5.18.18",
        "lessThan": "5.19",
        "versionType": "semver"
      }
    ],
    "programFiles": [
      "include/linux/bpf.h",
      "kernel/bpf/arraymap.c",
      "kernel/bpf/hashtab.c",
      "kernel/bpf/syscall.c",
      "tools/testing/selftests/bpf/prog_tests/htab_update.c",
      "tools/testing/selftests/bpf/prog_tests/linked_list.c",
      "tools/testing/selftests/bpf/prog_tests/map_kptr.c",
      "tools/testing/selftests/bpf/prog_tests/refcounted_kptr.c",
      "tools/testing/selftests/bpf/progs/htab_update.c",
      "tools/testing/selftests/bpf/progs/linked_list.c",
      "tools/testing/selftests/bpf/progs/refcounted_kptr.c"
    ],
    "defaultStatus": "unaffected"
  },
  {
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "vendor": "Linux",
    "product": "Linux",
    "versions": [
      {
        "status": "affected",
        "version": "5.19"
      },
      {
        "status": "unaffected",
        "version": "0",
        "lessThan": "5.19",
        "versionType": "semver"
      },
      {
        "status": "unaffected",
        "version": "7.1.5",
        "versionType": "semver",
        "lessThanOrEqual": "7.1.*"
      },
      {
        "status": "unaffected",
        "version": "7.2",
        "versionType": "original_commit_for_fix",
        "lessThanOrEqual": "*"
      }
    ],
    "programFiles": [
      "include/linux/bpf.h",
      "kernel/bpf/arraymap.c",
      "kernel/bpf/hashtab.c",
      "kernel/bpf/syscall.c",
      "tools/testing/selftests/bpf/prog_tests/htab_update.c",
      "tools/testing/selftests/bpf/prog_tests/linked_list.c",
      "tools/testing/selftests/bpf/prog_tests/map_kptr.c",
      "tools/testing/selftests/bpf/prog_tests/refcounted_kptr.c",
      "tools/testing/selftests/bpf/progs/htab_update.c",
      "tools/testing/selftests/bpf/progs/linked_list.c",
      "tools/testing/selftests/bpf/progs/refcounted_kptr.c"
    ],
    "defaultStatus": "affected"
  }
]
Related CVEs
CVE-2026-74314

Source reference: /cveMetadata/cveId

Publisher severity

high

Source reference: /containers/cna/metrics

Event
#33095 · Revision 1
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Publisher date
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