CVE-2026-64352
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.
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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:
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.
Detalles técnicos trazas, registros y código del informe original
=============================
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_64CVSS
- Versión: 3.1
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- Puntuación base: 7.8
Probabilidad de explotación (EPSS)
- Probabilidad de explotación en los próximos 30 días: 0.13%
- Percentil entre todas las CVEs puntuadas: 2
- Fecha de la puntuación: 6/10/2026
EPSS (Exploit Prediction Scoring System, de FIRST) estima la probabilidad de que una vulnerabilidad sea explotada en 30 días. Complementa a CVSS (impacto) y a CISA KEV (explotación confirmada).
🎯 Técnicas ATT&CK
Cómo se explota esta vulnerabilidad y qué consigue el atacante, en el lenguaje de MITRE ATT&CK.
- Explotación
T1068Exploitation for Privilege Escalationprivilege escalation75 % - Impacto principal
T1059Command and Scripting Interpreterexecution65 % - Impacto secundario
T1498.002Reflection Amplificationimpact35 %
Vulnerabilidad de escalada local (AV:L/PR:L) en kernel de Linux que permite bypass de verificaciones RCU en programas BPF sleepable, facilitando ejecución no autorizada de código con privilegios elevados mediante acceso a mapas LPM sin validación adecuada.
Inferido por nuestro agente de análisis a partir de la descripción oficial, el vector CVSS y la CWE, y comprobado por un supervisor. Puede contener errores.
🛡️ Mitigaciones ATT&CK que cubren estas técnicas
Tecnologías afectadas (1)
CWE
- CWE-416
Referencias
- https://git.kernel.org/stable/c/2f884d371fafea137afea504d49ee4a7c8d7985b
- https://git.kernel.org/stable/c/304ca50582f0c047370f85e13caec456f78c9fcc
- https://git.kernel.org/stable/c/57454944737f3ad9a8703aecbbb79713b513a94b
- https://git.kernel.org/stable/c/9bfdf4b81b0e56d47bc6c46c34a46638be716695
- https://git.kernel.org/stable/c/bd6ad9a6b30498d845413e863fb95c6fab3babe3
- https://git.kernel.org/stable/c/ec662a8b2cde01e76b37ccd4b992d0342299e69c
- https://git.kernel.org/stable/c/f0967d4f1ba4323a3cb7dc8fdba74dd3a8caaf04
JSON original (NVD)
Mostrar
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"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->lock (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's 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->lock is held across the walk. rqspinlock has no\nlockdep_map, so the predicate degenerates to '1' rather than\nlockdep_is_held(&trie->lock); 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."
}
],
"lastModified": "2026-09-03T16:03:25.423",
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