FKIE_CVE-2026-98789

Vulnerability from fkie_nvd - Published: 2026-10-18 16:17 - Updated: 2026-10-19 10:19
Severity
Summary
In the Linux kernel, the following vulnerability has been resolved: bpf: Fix objects stuck in free_by_rcu_ttrace do_call_rcu_ttrace() returns early when call_rcu_ttrace_in_progress is set and leaves the objects in free_by_rcu_ttrace. __free_rcu() frees waiting_for_gp_ttrace only and clears the flag. Hence the objects that free_bulk() or __free_by_rcu() added while RCU tasks trace GP was in flight stay in free_by_rcu_ttrace until free_bulk() or alloc_bulk() is called for the same bpf_mem_cache again, which may never happen. The number of such objects is not bounded. Turn call_rcu_ttrace_in_progress into three states: 0 - idle 1 - __free_rcu() is queued 2 - __free_rcu() is queued and free_by_rcu_ttrace got more objects since do_call_rcu_ttrace() sets 2. __free_rcu() does cmpxchg(1 -> 0) and starts the next GP when it fails. It cannot clear the flag first and check free_by_rcu_ttrace later, since bpf_mem_alloc_destroy() frees bpf_mem_cache without waiting for RCU callbacks when the flag is zero. Now __free_rcu() queues itself, so the one that didn't see 'draining' may do call_rcu_tasks_trace() after rcu_barrier_tasks_trace() in free_mem_alloc(). Queue it under rcu_read_lock() and do synchronize_rcu() before the barriers. Calling rcu_barrier_tasks_trace() twice works too, but creating and destroying hash maps in a loop on many cpus slows down to one free_mem_alloc() per GP and kworkers pile up.
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/33d0a5d2fee06a51f2f056dd901296515912e954
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/fbd97dd1d3ce32d32fb7be86acc3fdb7c04fa043
Impacted products
Vendor Product Version
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "kernel/bpf/memalloc.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "33d0a5d2fee06a51f2f056dd901296515912e954",
              "status": "affected",
              "version": "8d5a8011b35d387c490a5c977b1d9eb4798aa071",
              "versionType": "git"
            },
            {
              "lessThan": "fbd97dd1d3ce32d32fb7be86acc3fdb7c04fa043",
              "status": "affected",
              "version": "8d5a8011b35d387c490a5c977b1d9eb4798aa071",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "kernel/bpf/memalloc.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.1"
            },
            {
              "lessThan": "6.1",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.10",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Fix objects stuck in free_by_rcu_ttrace\n\ndo_call_rcu_ttrace() returns early when call_rcu_ttrace_in_progress is set\nand leaves the objects in free_by_rcu_ttrace. __free_rcu() frees\nwaiting_for_gp_ttrace only and clears the flag. Hence the objects that\nfree_bulk() or __free_by_rcu() added while RCU tasks trace GP was in flight\nstay in free_by_rcu_ttrace until free_bulk() or alloc_bulk() is called for\nthe same bpf_mem_cache again, which may never happen. The number of such\nobjects is not bounded.\n\nTurn call_rcu_ttrace_in_progress into three states:\n0 - idle\n1 - __free_rcu() is queued\n2 - __free_rcu() is queued and free_by_rcu_ttrace got more objects since\n\ndo_call_rcu_ttrace() sets 2. __free_rcu() does cmpxchg(1 -\u003e 0) and starts\nthe next GP when it fails. It cannot clear the flag first and check\nfree_by_rcu_ttrace later, since bpf_mem_alloc_destroy() frees bpf_mem_cache\nwithout waiting for RCU callbacks when the flag is zero.\n\nNow __free_rcu() queues itself, so the one that didn\u0027t see \u0027draining\u0027 may\ndo call_rcu_tasks_trace() after rcu_barrier_tasks_trace() in\nfree_mem_alloc(). Queue it under rcu_read_lock() and do synchronize_rcu()\nbefore the barriers. Calling rcu_barrier_tasks_trace() twice works too, but\ncreating and destroying hash maps in a loop on many cpus slows down to one\nfree_mem_alloc() per GP and kworkers pile up."
    }
  ],
  "id": "CVE-2026-98789",
  "lastModified": "2026-10-19T10:19:42.963",
  "metrics": {},
  "published": "2026-10-18T16:17:32.887",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/33d0a5d2fee06a51f2f056dd901296515912e954"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/fbd97dd1d3ce32d32fb7be86acc3fdb7c04fa043"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Received"
}



Log in or create an account to share your comment.




Tags
Taxonomy of the tags.




Drag nodes to arrange them. Double-click a related vulnerability to open it, or a source to visit its link. The Physics button on the left tunes the layout and the simulation; the legend at the bottom left hides or shows nodes by kind and by sighting type.

Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

Author Source Type Date Other

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
Vulnerability timeline

Sightings and recorded dates, grouped by day · UTC

JSON

Loading timeline…




    Related by attack behaviour

    Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.