GHSA-8QVR-6896-8WFM

Vulnerability from github – Published: 2026-06-24 18:32 – Updated: 2026-06-28 09:31
VLAI
Details

In the Linux kernel, the following vulnerability has been resolved:

bpf: Use RCU-safe iteration in dev_map_redirect_multi() SKB path

The DEVMAP_HASH branch in dev_map_redirect_multi() uses hlist_for_each_entry_safe() to iterate hash buckets, but this function runs under RCU protection (called from xdp_do_generic_redirect_map() in softirq context). Concurrent writers (__dev_map_hash_update_elem, dev_map_hash_delete_elem) modify the list using RCU primitives (hlist_add_head_rcu, hlist_del_rcu).

hlist_for_each_entry_safe() performs plain pointer dereferences without rcu_dereference(), missing the acquire barrier needed to pair with writers' rcu_assign_pointer(). On weakly-ordered architectures (ARM64, POWER), a reader can observe a partially-constructed node. It also defeats CONFIG_PROVE_RCU lockdep validation and KCSAN data-race detection.

Replace with hlist_for_each_entry_rcu() using rcu_read_lock_bh_held() as the lockdep condition, consistent with the rcu_dereference_check() used in the DEVMAP (non-hash) branch of the same functions. Also fix the same incorrect lockdep_is_held(&dtab->index_lock) condition in dev_map_enqueue_multi(), where the lock is not held either.

Severity
7.8 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
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{
  "affected": [],
  "aliases": [
    "CVE-2026-53096"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-06-24T17:17:23Z",
    "severity": "HIGH"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Use RCU-safe iteration in dev_map_redirect_multi() SKB path\n\nThe DEVMAP_HASH branch in dev_map_redirect_multi() uses\nhlist_for_each_entry_safe() to iterate hash buckets, but this function\nruns under RCU protection (called from xdp_do_generic_redirect_map()\nin softirq context). Concurrent writers (__dev_map_hash_update_elem,\ndev_map_hash_delete_elem) modify the list using RCU primitives\n(hlist_add_head_rcu, hlist_del_rcu).\n\nhlist_for_each_entry_safe() performs plain pointer dereferences without\nrcu_dereference(), missing the acquire barrier needed to pair with\nwriters\u0027 rcu_assign_pointer(). On weakly-ordered architectures (ARM64,\nPOWER), a reader can observe a partially-constructed node. It also\ndefeats CONFIG_PROVE_RCU lockdep validation and KCSAN data-race\ndetection.\n\nReplace with hlist_for_each_entry_rcu() using rcu_read_lock_bh_held()\nas the lockdep condition, consistent with the rcu_dereference_check()\nused in the DEVMAP (non-hash) branch of the same functions. Also fix\nthe same incorrect lockdep_is_held(\u0026dtab-\u003eindex_lock) condition in\ndev_map_enqueue_multi(), where the lock is not held either.",
  "id": "GHSA-8qvr-6896-8wfm",
  "modified": "2026-06-28T09:31:41Z",
  "published": "2026-06-24T18:32:46Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-53096"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/4a3d0fe30b907ff324b1b49756f7e713d67f3645"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/571a05ea1baaccc0dc1e0d227b2cbc978b96d392"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/7027e705062482a8cea43a1c13ede3c35653966f"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/8ed82f807bb09d2c8455aaa665f2c6cb17bc6a19"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/b089aa6e94d7a08e74d076a0fe274842dc9feccc"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/cb2c1f3cf65b855548e1b8d55a08bfbaa5a0901a"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/d4c4bd231ebad70e6f30db429e9640bf378b2f52"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ]
}


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