CVE-2026-98036

Full vulnerability record from the local CVENow database.

Description

In the Linux kernel, the following vulnerability has been resolved: bpf: Preserve special fields in recycled rhtab elements rhtab_map_update_elem() initializes special fields after obtaining an element from bpf_mem_cache_alloc(). The allocator can return a fresh, zeroed unit, or recycle one from its RCU-pending lists before the registered destructor has run. A BPF program can retain a map-value pointer after deleting its element and initialize and arm a timer through that pointer. If the deleted unit is recycled, check_and_init_map_value() clears the only pointer to the timer. Neither a later deletion nor rhtab_mem_dtor() can then cancel it, and the callback can run with its key and value pointing into freed memory. Do not reinitialize special fields on insertion. Fresh allocator units are already zeroed. For recycled units, the special fields are ownership state that must remain visible to the eventual destructor. copy_map_value() already skips those fields, matching the non-preallocated hash-map path and the lifecycle established by commit 275c30bcee66 ("bpf: Don't reinit map value in prealloc_lru_pop"). [ kkd: Split out the fix and rewrote the commit log ]

Severity

Not scored

CVSS score

Not available

Vulnerability status

Received

Source identifier

416baaa9-dc9f-4396-8d5f-8c081fb06d67

Published

2026-09-25 11:17:32.340000

Last modified

2026-10-19 10:17:57.567000

View original CVE JSON

{
  "id": "CVE-2026-98036",
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "published": "2026-09-25T11:17:32.340",
  "lastModified": "2026-10-19T10:17:57.567",
  "vulnStatus": "Received",
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Preserve special fields in recycled rhtab elements\n\nrhtab_map_update_elem() initializes special fields after obtaining an\nelement from bpf_mem_cache_alloc(). The allocator can return a fresh,\nzeroed unit, or recycle one from its RCU-pending lists before the\nregistered destructor has run.\n\nA BPF program can retain a map-value pointer after deleting its element\nand initialize and arm a timer through that pointer. If the deleted unit\nis recycled, check_and_init_map_value() clears the only pointer to the\ntimer. Neither a later deletion nor rhtab_mem_dtor() can then cancel it,\nand the callback can run with its key and value pointing into freed memory.\n\nDo not reinitialize special fields on insertion. Fresh allocator units are\nalready zeroed. For recycled units, the special fields are ownership state\nthat must remain visible to the eventual destructor. copy_map_value()\nalready skips those fields, matching the non-preallocated hash-map path and\nthe lifecycle established by commit 275c30bcee66 (\"bpf: Don't reinit map\nvalue in prealloc_lru_pop\").\n\n[ kkd: Split out the fix and rewrote the commit log ]"
    }
  ],
  "affected": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "affectedData": [
        {
          "vendor": "Linux",
          "product": "Linux",
          "defaultStatus": "unaffected",
          "programFiles": [
            "kernel/bpf/hashtab.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "versions": [
            {
              "version": "6905f8601298ecd2d1932a4b4849bf265201118e",
              "lessThan": "6a5266b8288216b86602ff687d528abfb066dfd8",
              "versionType": "git",
              "status": "affected"
            },
            {
              "version": "6905f8601298ecd2d1932a4b4849bf265201118e",
              "lessThan": "5df46ddcb7b36878c1b691e9057a0509042a2567",
              "versionType": "git",
              "status": "affected"
            }
          ]
        },
        {
          "vendor": "Linux",
          "product": "Linux",
          "defaultStatus": "affected",
          "programFiles": [
            "kernel/bpf/hashtab.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "versions": [
            {
              "version": "7.2",
              "status": "affected"
            },
            {
              "version": "0",
              "lessThan": "7.2",
              "versionType": "semver",
              "status": "unaffected"
            },
            {
              "version": "7.2.7",
              "lessThanOrEqual": "7.2.*",
              "versionType": "semver",
              "status": "unaffected"
            },
            {
              "version": "7.3",
              "lessThanOrEqual": "*",
              "versionType": "original_commit_for_fix",
              "status": "unaffected"
            }
          ]
        }
      ]
    }
  ],
  "metrics": {},
  "references": [
    {
      "url": "https://git.kernel.org/stable/c/5df46ddcb7b36878c1b691e9057a0509042a2567",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/6a5266b8288216b86602ff687d528abfb066dfd8",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ]
}