Vulnerability-Lookup

GHSA-RQC3-HGHM-Q589

Vulnerability from github – Published: 2024-12-27 15:31 – Updated: 2025-10-08 15:32

Details

In the Linux kernel, the following vulnerability has been resolved:

rcu/nocb: Fix missed RCU barrier on deoffloading

Currently, running rcutorture test with torture_type=rcu fwd_progress=8 n_barrier_cbs=8 nocbs_nthreads=8 nocbs_toggle=100 onoff_interval=60 test_boost=2, will trigger the following warning:

WARNING: CPU: 19 PID: 100 at kernel/rcu/tree_nocb.h:1061 rcu_nocb_rdp_deoffload+0x292/0x2a0
RIP: 0010:rcu_nocb_rdp_deoffload+0x292/0x2a0
 Call Trace:
  <TASK>
  ? __warn+0x7e/0x120
  ? rcu_nocb_rdp_deoffload+0x292/0x2a0
  ? report_bug+0x18e/0x1a0
  ? handle_bug+0x3d/0x70
  ? exc_invalid_op+0x18/0x70
  ? asm_exc_invalid_op+0x1a/0x20
  ? rcu_nocb_rdp_deoffload+0x292/0x2a0
  rcu_nocb_cpu_deoffload+0x70/0xa0
  rcu_nocb_toggle+0x136/0x1c0
  ? __pfx_rcu_nocb_toggle+0x10/0x10
  kthread+0xd1/0x100
  ? __pfx_kthread+0x10/0x10
  ret_from_fork+0x2f/0x50
  ? __pfx_kthread+0x10/0x10
  ret_from_fork_asm+0x1a/0x30
  </TASK>

CPU0 CPU2 CPU3 //rcu_nocb_toggle //nocb_cb_wait //rcutorture

// deoffload CPU1 // process CPU1's rdp rcu_barrier() rcu_segcblist_entrain() rcu_segcblist_add_len(1); // len == 2 // enqueue barrier // callback to CPU1's // rdp->cblist rcu_do_batch() // invoke CPU1's rdp->cblist // callback rcu_barrier_callback() rcu_barrier() mutex_lock(&rcu_state.barrier_mutex); // still see len == 2 // enqueue barrier callback // to CPU1's rdp->cblist rcu_segcblist_entrain() rcu_segcblist_add_len(1); // len == 3 // decrement len rcu_segcblist_add_len(-2); kthread_parkme()

// CPU1's rdp->cblist len == 1 // Warn because there is // still a pending barrier // trigger warning WARN_ON_ONCE(rcu_segcblist_n_cbs(&rdp->cblist)); cpus_read_unlock();

                                                            // wait CPU1 to comes online and
                                                            // invoke barrier callback on
                                                            // CPU1 rdp's->cblist
                                                            wait_for_completion(&rcu_state.barrier_completion);

// deoffload CPU4 cpus_read_lock() rcu_barrier() mutex_lock(&rcu_state.barrier_mutex); // block on barrier_mutex // wait rcu_barrier() on // CPU3 to unlock barrier_mutex // but CPU3 unlock barrier_mutex // need to wait CPU1 comes online // when CPU1 going online will block on cpus_write_lock

The above scenario will not only trigger a WARN_ON_ONCE(), but also trigger a deadlock.

Thanks to nocb locking, a second racing rcu_barrier() on an offline CPU will either observe the decremented callback counter down to 0 and spare the callback enqueue, or rcuo will observe the new callback and keep rdp->nocb_cb_sleep to false.

Therefore check rdp->nocb_cb_sleep before parking to make sure no further rcu_barrier() is waiting on the rdp.

Severity

4.7 (Medium)


                  
                    CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H

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{
  "affected": [],
  "aliases": [
    "CVE-2024-56547"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2024-12-27T14:15:34Z",
    "severity": "MODERATE"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nrcu/nocb: Fix missed RCU barrier on deoffloading\n\nCurrently, running rcutorture test with torture_type=rcu fwd_progress=8\nn_barrier_cbs=8 nocbs_nthreads=8 nocbs_toggle=100 onoff_interval=60\ntest_boost=2, will trigger the following warning:\n\n\tWARNING: CPU: 19 PID: 100 at kernel/rcu/tree_nocb.h:1061 rcu_nocb_rdp_deoffload+0x292/0x2a0\n\tRIP: 0010:rcu_nocb_rdp_deoffload+0x292/0x2a0\n\t Call Trace:\n\t  \u003cTASK\u003e\n\t  ? __warn+0x7e/0x120\n\t  ? rcu_nocb_rdp_deoffload+0x292/0x2a0\n\t  ? report_bug+0x18e/0x1a0\n\t  ? handle_bug+0x3d/0x70\n\t  ? exc_invalid_op+0x18/0x70\n\t  ? asm_exc_invalid_op+0x1a/0x20\n\t  ? rcu_nocb_rdp_deoffload+0x292/0x2a0\n\t  rcu_nocb_cpu_deoffload+0x70/0xa0\n\t  rcu_nocb_toggle+0x136/0x1c0\n\t  ? __pfx_rcu_nocb_toggle+0x10/0x10\n\t  kthread+0xd1/0x100\n\t  ? __pfx_kthread+0x10/0x10\n\t  ret_from_fork+0x2f/0x50\n\t  ? __pfx_kthread+0x10/0x10\n\t  ret_from_fork_asm+0x1a/0x30\n\t  \u003c/TASK\u003e\n\nCPU0                               CPU2                          CPU3\n//rcu_nocb_toggle             //nocb_cb_wait                   //rcutorture\n\n// deoffload CPU1             // process CPU1\u0027s rdp\nrcu_barrier()\n    rcu_segcblist_entrain()\n        rcu_segcblist_add_len(1);\n        // len == 2\n        // enqueue barrier\n        // callback to CPU1\u0027s\n        // rdp-\u003ecblist\n                             rcu_do_batch()\n                                 // invoke CPU1\u0027s rdp-\u003ecblist\n                                 // callback\n                                 rcu_barrier_callback()\n                                                             rcu_barrier()\n                                                               mutex_lock(\u0026rcu_state.barrier_mutex);\n                                                               // still see len == 2\n                                                               // enqueue barrier callback\n                                                               // to CPU1\u0027s rdp-\u003ecblist\n                                                               rcu_segcblist_entrain()\n                                                                   rcu_segcblist_add_len(1);\n                                                                   // len == 3\n                                 // decrement len\n                                 rcu_segcblist_add_len(-2);\n                             kthread_parkme()\n\n// CPU1\u0027s rdp-\u003ecblist len == 1\n// Warn because there is\n// still a pending barrier\n// trigger warning\nWARN_ON_ONCE(rcu_segcblist_n_cbs(\u0026rdp-\u003ecblist));\ncpus_read_unlock();\n\n                                                                // wait CPU1 to comes online and\n                                                                // invoke barrier callback on\n                                                                // CPU1 rdp\u0027s-\u003ecblist\n                                                                wait_for_completion(\u0026rcu_state.barrier_completion);\n// deoffload CPU4\ncpus_read_lock()\n  rcu_barrier()\n    mutex_lock(\u0026rcu_state.barrier_mutex);\n    // block on barrier_mutex\n    // wait rcu_barrier() on\n    // CPU3 to unlock barrier_mutex\n    // but CPU3 unlock barrier_mutex\n    // need to wait CPU1 comes online\n    // when CPU1 going online will block on cpus_write_lock\n\nThe above scenario will not only trigger a WARN_ON_ONCE(), but also\ntrigger a deadlock.\n\nThanks to nocb locking, a second racing rcu_barrier() on an offline CPU\nwill either observe the decremented callback counter down to 0 and spare\nthe callback enqueue, or rcuo will observe the new callback and keep\nrdp-\u003enocb_cb_sleep to false.\n\nTherefore check rdp-\u003enocb_cb_sleep before parking to make sure no\nfurther rcu_barrier() is waiting on the rdp.",
  "id": "GHSA-rqc3-hghm-q589",
  "modified": "2025-10-08T15:32:25Z",
  "published": "2024-12-27T15:31:53Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2024-56547"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/224b62028959858294789772d372dcb36cf5f820"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/2996980e20b7a54a1869df15b3445374b850b155"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    }
  ]
}

CVE-2024-56547 (GCVE-0-2024-56547)

Vulnerability from cvelistv5 – Published: 2024-12-27 14:11 – Updated: 2026-05-11 20:54

Title

rcu/nocb: Fix missed RCU barrier on deoffloading

Summary

In the Linux kernel, the following vulnerability has been resolved: rcu/nocb: Fix missed RCU barrier on deoffloading Currently, running rcutorture test with torture_type=rcu fwd_progress=8 n_barrier_cbs=8 nocbs_nthreads=8 nocbs_toggle=100 onoff_interval=60 test_boost=2, will trigger the following warning: WARNING: CPU: 19 PID: 100 at kernel/rcu/tree_nocb.h:1061 rcu_nocb_rdp_deoffload+0x292/0x2a0 RIP: 0010:rcu_nocb_rdp_deoffload+0x292/0x2a0 Call Trace: <TASK> ? __warn+0x7e/0x120 ? rcu_nocb_rdp_deoffload+0x292/0x2a0 ? report_bug+0x18e/0x1a0 ? handle_bug+0x3d/0x70 ? exc_invalid_op+0x18/0x70 ? asm_exc_invalid_op+0x1a/0x20 ? rcu_nocb_rdp_deoffload+0x292/0x2a0 rcu_nocb_cpu_deoffload+0x70/0xa0 rcu_nocb_toggle+0x136/0x1c0 ? __pfx_rcu_nocb_toggle+0x10/0x10 kthread+0xd1/0x100 ? __pfx_kthread+0x10/0x10 ret_from_fork+0x2f/0x50 ? __pfx_kthread+0x10/0x10 ret_from_fork_asm+0x1a/0x30 </TASK> CPU0 CPU2 CPU3 //rcu_nocb_toggle //nocb_cb_wait //rcutorture // deoffload CPU1 // process CPU1's rdp rcu_barrier() rcu_segcblist_entrain() rcu_segcblist_add_len(1); // len == 2 // enqueue barrier // callback to CPU1's // rdp->cblist rcu_do_batch() // invoke CPU1's rdp->cblist // callback rcu_barrier_callback() rcu_barrier() mutex_lock(&rcu_state.barrier_mutex); // still see len == 2 // enqueue barrier callback // to CPU1's rdp->cblist rcu_segcblist_entrain() rcu_segcblist_add_len(1); // len == 3 // decrement len rcu_segcblist_add_len(-2); kthread_parkme() // CPU1's rdp->cblist len == 1 // Warn because there is // still a pending barrier // trigger warning WARN_ON_ONCE(rcu_segcblist_n_cbs(&rdp->cblist)); cpus_read_unlock(); // wait CPU1 to comes online and // invoke barrier callback on // CPU1 rdp's->cblist wait_for_completion(&rcu_state.barrier_completion); // deoffload CPU4 cpus_read_lock() rcu_barrier() mutex_lock(&rcu_state.barrier_mutex); // block on barrier_mutex // wait rcu_barrier() on // CPU3 to unlock barrier_mutex // but CPU3 unlock barrier_mutex // need to wait CPU1 comes online // when CPU1 going online will block on cpus_write_lock The above scenario will not only trigger a WARN_ON_ONCE(), but also trigger a deadlock. Thanks to nocb locking, a second racing rcu_barrier() on an offline CPU will either observe the decremented callback counter down to 0 and spare the callback enqueue, or rcuo will observe the new callback and keep rdp->nocb_cb_sleep to false. Therefore check rdp->nocb_cb_sleep before parking to make sure no further rcu_barrier() is waiting on the rdp.

Severity

No CVSS data available.

Assigner

Linux mitre root Scorecard

References

2 references

URL	Tags
https://git.kernel.org/stable/c/224b6202895985829…
https://git.kernel.org/stable/c/2996980e20b7a54a1…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: 1fcb932c8b5ce86219d7dedcd63659351a43291c , < 224b62028959858294789772d372dcb36cf5f820 (git) Affected: 1fcb932c8b5ce86219d7dedcd63659351a43291c , < 2996980e20b7a54a1869df15b3445374b850b155 (git)
Linux	Linux	Affected: 6.12 Unaffected: 0 , < 6.12 (semver) Unaffected: 6.12.2 , ≤ 6.12.* (semver) Unaffected: 6.13 , ≤ * (original_commit_for_fix)

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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "kernel/rcu/tree_nocb.h"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "224b62028959858294789772d372dcb36cf5f820",
              "status": "affected",
              "version": "1fcb932c8b5ce86219d7dedcd63659351a43291c",
              "versionType": "git"
            },
            {
              "lessThan": "2996980e20b7a54a1869df15b3445374b850b155",
              "status": "affected",
              "version": "1fcb932c8b5ce86219d7dedcd63659351a43291c",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "kernel/rcu/tree_nocb.h"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.12"
            },
            {
              "lessThan": "6.12",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.2",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "6.13",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.2",
                  "versionStartIncluding": "6.12",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.13",
                  "versionStartIncluding": "6.12",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nrcu/nocb: Fix missed RCU barrier on deoffloading\n\nCurrently, running rcutorture test with torture_type=rcu fwd_progress=8\nn_barrier_cbs=8 nocbs_nthreads=8 nocbs_toggle=100 onoff_interval=60\ntest_boost=2, will trigger the following warning:\n\n\tWARNING: CPU: 19 PID: 100 at kernel/rcu/tree_nocb.h:1061 rcu_nocb_rdp_deoffload+0x292/0x2a0\n\tRIP: 0010:rcu_nocb_rdp_deoffload+0x292/0x2a0\n\t Call Trace:\n\t  \u003cTASK\u003e\n\t  ? __warn+0x7e/0x120\n\t  ? rcu_nocb_rdp_deoffload+0x292/0x2a0\n\t  ? report_bug+0x18e/0x1a0\n\t  ? handle_bug+0x3d/0x70\n\t  ? exc_invalid_op+0x18/0x70\n\t  ? asm_exc_invalid_op+0x1a/0x20\n\t  ? rcu_nocb_rdp_deoffload+0x292/0x2a0\n\t  rcu_nocb_cpu_deoffload+0x70/0xa0\n\t  rcu_nocb_toggle+0x136/0x1c0\n\t  ? __pfx_rcu_nocb_toggle+0x10/0x10\n\t  kthread+0xd1/0x100\n\t  ? __pfx_kthread+0x10/0x10\n\t  ret_from_fork+0x2f/0x50\n\t  ? __pfx_kthread+0x10/0x10\n\t  ret_from_fork_asm+0x1a/0x30\n\t  \u003c/TASK\u003e\n\nCPU0                               CPU2                          CPU3\n//rcu_nocb_toggle             //nocb_cb_wait                   //rcutorture\n\n// deoffload CPU1             // process CPU1\u0027s rdp\nrcu_barrier()\n    rcu_segcblist_entrain()\n        rcu_segcblist_add_len(1);\n        // len == 2\n        // enqueue barrier\n        // callback to CPU1\u0027s\n        // rdp-\u003ecblist\n                             rcu_do_batch()\n                                 // invoke CPU1\u0027s rdp-\u003ecblist\n                                 // callback\n                                 rcu_barrier_callback()\n                                                             rcu_barrier()\n                                                               mutex_lock(\u0026rcu_state.barrier_mutex);\n                                                               // still see len == 2\n                                                               // enqueue barrier callback\n                                                               // to CPU1\u0027s rdp-\u003ecblist\n                                                               rcu_segcblist_entrain()\n                                                                   rcu_segcblist_add_len(1);\n                                                                   // len == 3\n                                 // decrement len\n                                 rcu_segcblist_add_len(-2);\n                             kthread_parkme()\n\n// CPU1\u0027s rdp-\u003ecblist len == 1\n// Warn because there is\n// still a pending barrier\n// trigger warning\nWARN_ON_ONCE(rcu_segcblist_n_cbs(\u0026rdp-\u003ecblist));\ncpus_read_unlock();\n\n                                                                // wait CPU1 to comes online and\n                                                                // invoke barrier callback on\n                                                                // CPU1 rdp\u0027s-\u003ecblist\n                                                                wait_for_completion(\u0026rcu_state.barrier_completion);\n// deoffload CPU4\ncpus_read_lock()\n  rcu_barrier()\n    mutex_lock(\u0026rcu_state.barrier_mutex);\n    // block on barrier_mutex\n    // wait rcu_barrier() on\n    // CPU3 to unlock barrier_mutex\n    // but CPU3 unlock barrier_mutex\n    // need to wait CPU1 comes online\n    // when CPU1 going online will block on cpus_write_lock\n\nThe above scenario will not only trigger a WARN_ON_ONCE(), but also\ntrigger a deadlock.\n\nThanks to nocb locking, a second racing rcu_barrier() on an offline CPU\nwill either observe the decremented callback counter down to 0 and spare\nthe callback enqueue, or rcuo will observe the new callback and keep\nrdp-\u003enocb_cb_sleep to false.\n\nTherefore check rdp-\u003enocb_cb_sleep before parking to make sure no\nfurther rcu_barrier() is waiting on the rdp."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-05-11T20:54:27.563Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/224b62028959858294789772d372dcb36cf5f820"
        },
        {
          "url": "https://git.kernel.org/stable/c/2996980e20b7a54a1869df15b3445374b850b155"
        }
      ],
      "title": "rcu/nocb: Fix missed RCU barrier on deoffloading",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2024-56547",
    "datePublished": "2024-12-27T14:11:28.548Z",
    "dateReserved": "2024-12-27T14:03:05.989Z",
    "dateUpdated": "2026-05-11T20:54:27.563Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

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Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
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GHSA-RQC3-HGHM-Q589

CVE-2024-56547 (GCVE-0-2024-56547)

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