GHSA-QF5H-QR5Q-G3PC
Vulnerability from github – Published: 2026-09-11 21:31 – Updated: 2026-09-14 15:32In the Linux kernel, the following vulnerability has been resolved:
SUNRPC: Check svc pool percpu counter allocation
__svc_create() initializes three per-pool percpu_counter stats and ignores every return value. On SMP, percpu_counter_init() fails when __alloc_percpu_gfp() cannot satisfy the allocation, leaving the failed counter with fbc->counters == NULL and its embedded raw_spinlock_t, list_head, and count never initialized. __svc_create() returns the half-constructed svc_serv to nfsd, lockd, or the NFS callback service anyway.
Once that service is live, the hot-path increments in svc_xprt_enqueue(), svc_handle_xprt(), and svc_pool_wake_idle_thread() reach a counter whose backing pointer is NULL. The pointer is a per-cpu offset, so the access does not fault: it resolves to offset zero of the current CPU's per-cpu area and silently corrupts whatever variable lives there. A /proc/fs/nfsd/pool_stats read walks the same NULL per-cpu storage and returns garbage, and on CONFIG_DEBUG_SPINLOCK or lockdep it splats on the never-initialized lock.
Creating the broken service requires a percpu allocation failure during RPC server startup, so it is reachable only by a local administrator under memory pressure or fault injection; a remote peer cannot induce the bad state on its own.
Check each percpu_counter_init() return value in __svc_create() and fail when an allocation fails, unwinding the counters already set up in the current pool and in every pool initialized before it. A discrete percpu_counter_destroy() per counter at teardown frees each per-cpu allocation exactly once.
{
"affected": [],
"aliases": [
"CVE-2026-89547"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-09-11T20:19:38Z",
"severity": "HIGH"
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nSUNRPC: Check svc pool percpu counter allocation\n\n__svc_create() initializes three per-pool percpu_counter stats and\nignores every return value. On SMP, percpu_counter_init() fails when\n__alloc_percpu_gfp() cannot satisfy the allocation, leaving the failed\ncounter with fbc-\u003ecounters == NULL and its embedded raw_spinlock_t,\nlist_head, and count never initialized. __svc_create() returns the\nhalf-constructed svc_serv to nfsd, lockd, or the NFS callback service\nanyway.\n\nOnce that service is live, the hot-path increments in\nsvc_xprt_enqueue(), svc_handle_xprt(), and\nsvc_pool_wake_idle_thread() reach a counter whose backing pointer is\nNULL. The pointer is a per-cpu offset, so the access does not fault:\nit resolves to offset zero of the current CPU\u0027s per-cpu area and\nsilently corrupts whatever variable lives there. A\n/proc/fs/nfsd/pool_stats read walks the same NULL per-cpu storage and\nreturns garbage, and on CONFIG_DEBUG_SPINLOCK or lockdep it splats on\nthe never-initialized lock.\n\nCreating the broken service requires a percpu allocation failure during\nRPC server startup, so it is reachable only by a local administrator\nunder memory pressure or fault injection; a remote peer cannot induce\nthe bad state on its own.\n\nCheck each percpu_counter_init() return value in __svc_create() and\nfail when an allocation fails, unwinding the counters already set up\nin the current pool and in every pool initialized before it. A\ndiscrete percpu_counter_destroy() per counter at teardown frees each\nper-cpu allocation exactly once.",
"id": "GHSA-qf5h-qr5q-g3pc",
"modified": "2026-09-14T15:32:28Z",
"published": "2026-09-11T21:31:31Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-89547"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/3a2b7649de76376a69f1d3ed2a539fb15907cd4d"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/43e11e164704dde975c9edb370de1a06bec67270"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/57ac7d899409b0a9b768cf417e3bb86bcca3d4c6"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/b541a15046976e481618726cc23db0fb22d576db"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/bd1ef2cfb44d72b7aa6943e87b206eb0e30fbd0c"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H",
"type": "CVSS_V3"
}
]
}
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