{"cve":"CVE-2025-39886","nvd":{"published":"2025-09-23T06:15:48.680","modified":"2026-10-19T21:10:00.160","status":"Modified","description":"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/20250905201606.66198-1-shakeel.butt@linux.dev/\n\nv0 approach s/bpf_map_kmalloc_node/bpf_mem_alloc/\nhttps://lore.kernel.org/bpf/20250905061919.439648-1-yepeilin@google.com/\nv1 approach:\nhttps://lore.kernel.org/bpf/20250905234547.862249-1-yepeilin@google.com/","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","score":5.5},"cwes":[],"references":["https://git.kernel.org/stable/c/449682e76f32601f211816d3e2100bed87e67a4c","https://git.kernel.org/stable/c/6d78b4473cdb08b74662355a9e8510bde09c511e","https://git.kernel.org/stable/c/ac70cd446f83ccb25532b343919ab86eacdcd06a","https://git.kernel.org/stable/c/cd1fd26bb13473c1734e3026b2b97025a0a4087b"],"products":["linux:linux_kernel"],"source":"nvd","synced_at":"2026-10-21T03:43:09.190223697+00:00"},"epss":{"cve":"CVE-2025-39886","score":0.00151,"percentile":0.04224,"date":"2026-10-25"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}