CVE-2025-39886
Full vulnerability record from the local CVENow database.
Description
In the Linux kernel, the following vulnerability has been resolved: bpf: Tell memcg to use allow_spinning=false path in bpf_timer_init() Currently, calling bpf_map_kmalloc_node() from __bpf_async_init() can cause various locking issues; see the following stack trace (edited for style) as one example: ... [10.011566] do_raw_spin_lock.cold [10.011570] try_to_wake_up (5) double-acquiring the same [10.011575] kick_pool rq_lock, causing a hardlockup [10.011579] __queue_work [10.011582] queue_work_on [10.011585] kernfs_notify [10.011589] cgroup_file_notify [10.011593] try_charge_memcg (4) memcg accounting raises an [10.011597] obj_cgroup_charge_pages MEMCG_MAX event [10.011599] obj_cgroup_charge_account [10.011600] __memcg_slab_post_alloc_hook [10.011603] __kmalloc_node_noprof ... [10.011611] bpf_map_kmalloc_node [10.011612] __bpf_async_init [10.011615] bpf_timer_init (3) BPF calls bpf_timer_init() [10.011617] bpf_prog_xxxxxxxxxxxxxxxx_fcg_runnable [10.011619] bpf__sched_ext_ops_runnable [10.011620] enqueue_task_scx (2) BPF runs with rq_lock held [10.011622] enqueue_task [10.011626] ttwu_do_activate [10.011629] sched_ttwu_pending (1) grabs rq_lock ... The above was reproduced on bpf-next (b338cf849ec8) by modifying ./tools/sched_ext/scx_flatcg.bpf.c to call bpf_timer_init() during ops.runnable(), and hacking the memcg accounting code a bit to make a bpf_timer_init() call more likely to raise an MEMCG_MAX event. We have also run into other similar variants (both internally and on bpf-next), including double-acquiring cgroup_file_kn_lock, the same worker_pool::lock, etc. As suggested by Shakeel, fix this by using __GFP_HIGH instead of GFP_ATOMIC in __bpf_async_init(), so that e.g. if try_charge_memcg() raises an MEMCG_MAX event, we call __memcg_memory_event() with @allow_spinning=false and avoid calling cgroup_file_notify() there. Depends on mm patch "memcg: skip cgroup_file_notify if spinning is not allowed": https://lore.kernel.org/bpf/[email protected]/ v0 approach s/bpf_map_kmalloc_node/bpf_mem_alloc/ https://lore.kernel.org/bpf/[email protected]/ v1 approach: https://lore.kernel.org/bpf/[email protected]/
Severity
MEDIUM
CVSS score
5.5
(v3.1)
Vulnerability status
Modified
Source identifier
416baaa9-dc9f-4396-8d5f-8c081fb06d67
Published
2025-09-23 06:15:48.680000
Last modified
2026-10-30 13:18:10.963000
View original CVE JSON
{
"id": "CVE-2025-39886",
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"published": "2025-09-23T06:15:48.680",
"lastModified": "2026-10-30T13:18:10.963",
"vulnStatus": "Modified",
"cveTags": [],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Tell memcg to use allow_spinning=false path in bpf_timer_init()\n\nCurrently, calling bpf_map_kmalloc_node() from __bpf_async_init() can\ncause various locking issues; see the following stack trace (edited for\nstyle) as one example:\n\n...\n [10.011566] do_raw_spin_lock.cold\n [10.011570] try_to_wake_up (5) double-acquiring the same\n [10.011575] kick_pool rq_lock, causing a hardlockup\n [10.011579] __queue_work\n [10.011582] queue_work_on\n [10.011585] kernfs_notify\n [10.011589] cgroup_file_notify\n [10.011593] try_charge_memcg (4) memcg accounting raises an\n [10.011597] obj_cgroup_charge_pages MEMCG_MAX event\n [10.011599] obj_cgroup_charge_account\n [10.011600] __memcg_slab_post_alloc_hook\n [10.011603] __kmalloc_node_noprof\n...\n [10.011611] bpf_map_kmalloc_node\n [10.011612] __bpf_async_init\n [10.011615] bpf_timer_init (3) BPF calls bpf_timer_init()\n [10.011617] bpf_prog_xxxxxxxxxxxxxxxx_fcg_runnable\n [10.011619] bpf__sched_ext_ops_runnable\n [10.011620] enqueue_task_scx (2) BPF runs with rq_lock held\n [10.011622] enqueue_task\n [10.011626] ttwu_do_activate\n [10.011629] sched_ttwu_pending (1) grabs rq_lock\n...\n\nThe above was reproduced on bpf-next (b338cf849ec8) by modifying\n./tools/sched_ext/scx_flatcg.bpf.c to call bpf_timer_init() during\nops.runnable(), and hacking the memcg accounting code a bit to make\na bpf_timer_init() call more likely to raise an MEMCG_MAX event.\n\nWe have also run into other similar variants (both internally and on\nbpf-next), including double-acquiring cgroup_file_kn_lock, the same\nworker_pool::lock, etc.\n\nAs suggested by Shakeel, fix this by using __GFP_HIGH instead of\nGFP_ATOMIC in __bpf_async_init(), so that e.g. if try_charge_memcg()\nraises an MEMCG_MAX event, we call __memcg_memory_event() with\n@allow_spinning=false and avoid calling cgroup_file_notify() there.\n\nDepends on mm patch\n\"memcg: skip cgroup_file_notify if spinning is not allowed\":\nhttps://lore.kernel.org/bpf/[email protected]/\n\nv0 approach s/bpf_map_kmalloc_node/bpf_mem_alloc/\nhttps://lore.kernel.org/bpf/[email protected]/\nv1 approach:\nhttps://lore.kernel.org/bpf/[email protected]/"
},
{
"lang": "es",
"value": "En el kernel de Linux, la siguiente vulnerabilidad ha sido resuelta:\n\nbpf: Indicar a memcg que use la ruta allow_spinning=false en bpf_timer_init()\n\nActualmente, llamar a bpf_map_kmalloc_node() desde __bpf_async_init() puede causar varios problemas de bloqueo; ver el siguiente rastreo de pila (editado por estilo) como un ejemplo:\n\n...\n [10.011566] do_raw_spin_lock.cold\n [10.011570] try_to_wake_up (5) adquiriendo dos veces el mismo\n [10.011575] kick_pool rq_lock, causando un bloqueo total (hardlockup)\n [10.011579] __queue_work\n [10.011582] queue_work_on\n [10.011585] kernfs_notify\n [10.011589] cgroup_file_notify\n [10.011593] try_charge_memcg (4) la contabilidad de memcg eleva un\n [10.011597] obj_cgroup_charge_pages evento MEMCG_MAX\n [10.011599] obj_cgroup_charge_account\n [10.011600] __memcg_slab_post_alloc_hook\n [10.011603] __kmalloc_node_noprof\n...\n [10.011611] bpf_map_kmalloc_node\n [10.011612] __bpf_async_init\n [10.011615] bpf_timer_init (3) BPF llama a bpf_timer_init()\n [10.011617] bpf_prog_xxxxxxxxxxxxxxxx_fcg_runnable\n [10.011619] bpf__sched_ext_ops_runnable\n [10.011620] enqueue_task_scx (2) BPF se ejecuta con rq_lock retenido\n [10.011622] enqueue_task\n [10.011626] ttwu_do_activate\n [10.011629] sched_ttwu_pending (1) toma rq_lock\n...\n\nLo anterior fue reproducido en bpf-next (b338cf849ec8) modificando ./tools/sched_ext/scx_flatcg.bpf.c para llamar a bpf_timer_init() durante ops.runnable(), y modificando un poco el código de contabilidad de memcg para hacer que una llamada a bpf_timer_init() sea más propensa a elevar un evento MEMCG_MAX.\n\nTambién nos hemos encontrado con otras variantes similares (tanto internamente como en bpf-next), incluyendo la doble adquisición de cgroup_file_kn_lock, el mismo worker_pool::lock, etc.\n\nComo sugirió Shakeel, solucionar esto usando __GFP_HIGH en lugar de GFP_ATOMIC en __bpf_async_init(), de modo que, por ejemplo, si try_charge_memcg() eleva un evento MEMCG_MAX, llamamos a __memcg_memory_event() con @allow_spinning=false y evitamos llamar a cgroup_file_notify() allí.\n\nDepende del parche mm 'memcg: omitir cgroup_file_notify si no se permite el spinning':\nhttps://lore.kernel.org/bpf/[email protected]/\n\nEnfoque v0 s/bpf_map_kmalloc_node/bpf_mem_alloc/\nhttps://lore.kernel.org/bpf/[email protected]/\nEnfoque v1:\nhttps://lore.kernel.org/bpf/[email protected]/"
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