CVE-2026-89547 (GCVE-0-2026-89547)
Vulnerability from cvelistv5
Published
2026-09-11 19:44
Modified
2026-10-19 08:48
Severity ?
8.1 (High) - CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Summary
In 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.
References
Impacted products
Vendor Product Version
Linux Linux Version: ccf08bed6e7a80519569456edd2ea21b7b1701c6
Version: ccf08bed6e7a80519569456edd2ea21b7b1701c6
Version: ccf08bed6e7a80519569456edd2ea21b7b1701c6
Version: ccf08bed6e7a80519569456edd2ea21b7b1701c6
Version: ccf08bed6e7a80519569456edd2ea21b7b1701c6
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/sunrpc/svc.c"
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        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
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          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.3"
            },
            {
              "lessThan": "6.3",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.157",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.109",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.50",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.4",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.6.157",
                  "versionStartIncluding": "6.3",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.109",
                  "versionStartIncluding": "6.3",
                  "vulnerable": true
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                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.50",
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                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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              "negate": false,
              "operator": "OR"
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          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "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."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 8.1,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:N - After nfsd, lockd, or the NFS-callback SUNRPC service is created with a failed pool percpu_counter, svc_xprt_enqueue(), svc_handle_xprt(), and svc_pool_wake_idle_thread() increment those counters on the packet-receive hot path, so a remote NFS/NLM/callback peer triggers the corruption by sending RPC traffic (typically TCP/2049).\nAC:H - The broken service exists only if percpu_counter_init() fails inside __svc_create() during RPC server startup; that tiny per-CPU allocation failure requires memory pressure or fault injection that a remote peer cannot induce, so success depends on a startup condition the attacker cannot control.\nPR:N - svc_xprt_enqueue() and svc_handle_xprt() run when a SUNRPC transport has received data, before RPC authentication, so an unauthenticated network client needs no host account or capabilities to deliver the traffic that hits the NULL counters.\nUI:N - Exploitation is inbound RPC to an already-running nfsd, lockd, or NFS callback listener; no administrator or end-user action such as mounting a filesystem or opening a file is required at exploit time.\nS:U - Per-CPU corruption, pool_stats disclosure, and any resulting oops stay inside the host kernel\u0027s SUNRPC/nfsd authority and do not cross a VM, IOMMU, or other security boundary.\nC:H - A NULL fbc-\u003ecounters pointer is treated as a per-CPU offset, so increments and percpu_counter_sum_positive() read offset 0 of each CPU\u0027s per-CPU area; world-readable nfsd pool_stats returns those values, giving a kernel-memory disclosure primitive from the same corruption.\nI:H - percpu_counter_inc() cmpxchg-increments and the batch-fold path later zeroes the s32 at per-CPU offset 0 via __this_cpu_sub(), silently corrupting whatever kernel per-CPU variable lives there and yielding a write primitive against that storage rather than a contained stats-only update.\nA:H - The never-initialized counter lock/lockdep map can splat under CONFIG_DEBUG_SPINLOCK or lockdep, and corrupting the CPU\u0027s per-CPU area can oops or panic the host, so the bug is a kernel crash/DoS even when not fully exploited."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-19T08:48:38.898Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/57ac7d899409b0a9b768cf417e3bb86bcca3d4c6"
        },
        {
          "url": "https://git.kernel.org/stable/c/3a2b7649de76376a69f1d3ed2a539fb15907cd4d"
        },
        {
          "url": "https://git.kernel.org/stable/c/bd1ef2cfb44d72b7aa6943e87b206eb0e30fbd0c"
        },
        {
          "url": "https://git.kernel.org/stable/c/b541a15046976e481618726cc23db0fb22d576db"
        },
        {
          "url": "https://git.kernel.org/stable/c/43e11e164704dde975c9edb370de1a06bec67270"
        }
      ],
      "title": "SUNRPC: Check svc pool percpu counter allocation",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-89547",
    "datePublished": "2026-09-11T19:44:22.644Z",
    "dateReserved": "2026-09-11T19:38:34.722Z",
    "dateUpdated": "2026-10-19T08:48:38.898Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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