CVE-2026-64352 (GCVE-0-2026-64352)
Vulnerability from cvelistv5
Published
2026-07-25 08:50
Modified
2026-08-17 04:53
Severity ?
Summary
In the Linux kernel, the following vulnerability has been resolved: bpf: Allow LPM map access from sleepable BPF programs trie_lookup_elem() annotates its rcu_dereference_check() walks with only rcu_read_lock_bh_held(). Because rcu_dereference_check(p, c) resolves to "c || rcu_read_lock_held()", this passes for XDP/NAPI and classic RCU readers but fails for sleepable BPF programs, which enter via __bpf_prog_enter_sleepable() and hold only rcu_read_lock_trace(). trie_update_elem() and trie_delete_elem() have the same problem in a different form: they walk the trie with plain rcu_dereference(), which asserts rcu_read_lock_held() unconditionally. Both are reachable from sleepable BPF programs via the bpf_map_update_elem / bpf_map_delete_elem helpers, and from the syscall path under classic rcu_read_lock(). In the writer paths the trie is actually protected by trie->lock (an rqspinlock taken across the walk); we never relied on the RCU read-side lock to keep nodes alive there. A sleepable LSM hook that ends up touching an LPM trie therefore triggers lockdep on debug kernels: ============================= WARNING: suspicious RCU usage 7.1.0-... Tainted: G E ----------------------------- kernel/bpf/lpm_trie.c:249 suspicious rcu_dereference_check() usage! 1 lock held by net_tests/540: #0: (rcu_tasks_trace_srcu_struct){....}-{0:0}, at: __bpf_prog_enter_sleepable+0x26/0x280 Call Trace: dump_stack_lvl lockdep_rcu_suspicious trie_lookup_elem bpf_prog_..._enforce_security_socket_connect bpf_trampoline_... security_socket_connect __sys_connect do_syscall_64 This is lockdep-only -- no UAF, since Tasks Trace RCU does serialize against the trie's reclaim path -- but it spams the console once per distinct callsite on every debug kernel running a sleepable BPF LSM that touches an LPM trie, which is increasingly common. For the lookup path, switch the rcu_dereference_check() annotation from rcu_read_lock_bh_held() to bpf_rcu_lock_held(), which accepts all three contexts (classic, BH, Tasks Trace). Other map types already follow this convention. For trie_update_elem() and trie_delete_elem(), annotate the walks as rcu_dereference_protected(*p, 1) -- matching trie_free() in the same file -- since trie->lock is held across the walk. rqspinlock has no lockdep_map, so the predicate degenerates to '1' rather than lockdep_is_held(&trie->lock); the protection is real but not machine-verifiable. trie_get_next_key() also uses bare rcu_dereference() but is reachable only from the BPF syscall, which holds classic rcu_read_lock() before dispatching, so it is left untouched.
References
Impacted products
Vendor Product Version
Linux Linux Version: 694cea395fded425008e93cd90cfdf7a451674af
Version: 694cea395fded425008e93cd90cfdf7a451674af
Version: 694cea395fded425008e93cd90cfdf7a451674af
Version: 694cea395fded425008e93cd90cfdf7a451674af
Version: 694cea395fded425008e93cd90cfdf7a451674af
Version: 694cea395fded425008e93cd90cfdf7a451674af
Version: 694cea395fded425008e93cd90cfdf7a451674af
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{
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          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "kernel/bpf/lpm_trie.c"
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      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Allow LPM map access from sleepable BPF programs\n\ntrie_lookup_elem() annotates its rcu_dereference_check() walks with\nonly rcu_read_lock_bh_held().  Because rcu_dereference_check(p, c)\nresolves to \"c || rcu_read_lock_held()\", this passes for XDP/NAPI and\nclassic RCU readers but fails for sleepable BPF programs, which enter\nvia __bpf_prog_enter_sleepable() and hold only rcu_read_lock_trace().\n\ntrie_update_elem() and trie_delete_elem() have the same problem in a\ndifferent form: they walk the trie with plain rcu_dereference(), which\nasserts rcu_read_lock_held() unconditionally.  Both are reachable from\nsleepable BPF programs via the bpf_map_update_elem / bpf_map_delete_elem\nhelpers, and from the syscall path under classic rcu_read_lock().  In\nthe writer paths the trie is actually protected by trie-\u003elock (an\nrqspinlock taken across the walk); we never relied on the RCU read-side\nlock to keep nodes alive there.\n\nA sleepable LSM hook that ends up touching an LPM trie therefore\ntriggers lockdep on debug kernels:\n\n  =============================\n  WARNING: suspicious RCU usage\n  7.1.0-... Tainted: G            E\n  -----------------------------\n  kernel/bpf/lpm_trie.c:249 suspicious rcu_dereference_check() usage!\n  1 lock held by net_tests/540:\n   #0: (rcu_tasks_trace_srcu_struct){....}-{0:0},\n       at: __bpf_prog_enter_sleepable+0x26/0x280\n  Call Trace:\n   dump_stack_lvl\n   lockdep_rcu_suspicious\n   trie_lookup_elem\n   bpf_prog_..._enforce_security_socket_connect\n   bpf_trampoline_...\n   security_socket_connect\n   __sys_connect\n   do_syscall_64\n\nThis is lockdep-only -- no UAF, since Tasks Trace RCU does serialize\nagainst the trie\u0027s reclaim path -- but it spams the console once per\ndistinct callsite on every debug kernel running a sleepable BPF LSM\nthat touches an LPM trie, which is increasingly common.\n\nFor the lookup path, switch the rcu_dereference_check() annotation\nfrom rcu_read_lock_bh_held() to bpf_rcu_lock_held(), which accepts all\nthree contexts (classic, BH, Tasks Trace).  Other map types already\nfollow this convention.\n\nFor trie_update_elem() and trie_delete_elem(), annotate the walks as\nrcu_dereference_protected(*p, 1) -- matching trie_free() in the same\nfile -- since trie-\u003elock is held across the walk.  rqspinlock has no\nlockdep_map, so the predicate degenerates to \u00271\u0027 rather than\nlockdep_is_held(\u0026trie-\u003elock); the protection is real but not\nmachine-verifiable.  trie_get_next_key() also uses bare\nrcu_dereference() but is reachable only from the BPF syscall, which\nholds classic rcu_read_lock() before dispatching, so it is left\nuntouched."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-17T04:53:57.862Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/f0967d4f1ba4323a3cb7dc8fdba74dd3a8caaf04"
        },
        {
          "url": "https://git.kernel.org/stable/c/304ca50582f0c047370f85e13caec456f78c9fcc"
        },
        {
          "url": "https://git.kernel.org/stable/c/ec662a8b2cde01e76b37ccd4b992d0342299e69c"
        },
        {
          "url": "https://git.kernel.org/stable/c/9bfdf4b81b0e56d47bc6c46c34a46638be716695"
        },
        {
          "url": "https://git.kernel.org/stable/c/57454944737f3ad9a8703aecbbb79713b513a94b"
        },
        {
          "url": "https://git.kernel.org/stable/c/bd6ad9a6b30498d845413e863fb95c6fab3babe3"
        },
        {
          "url": "https://git.kernel.org/stable/c/2f884d371fafea137afea504d49ee4a7c8d7985b"
        }
      ],
      "title": "bpf: Allow LPM map access from sleepable BPF programs",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-64352",
    "datePublished": "2026-07-25T08:50:11.522Z",
    "dateReserved": "2026-07-19T15:36:31.782Z",
    "dateUpdated": "2026-08-17T04:53:57.862Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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