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

Vulnerability from cvelistv5 – Published: 2024-12-27 14:11 – Updated: 2026-05-11 20:54
VLAI
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
4.7 (Medium)
CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 1fcb932c8b5ce86219d7dedcd63659351a43291c , < 224b62028959858294789772d372dcb36cf5f820 (git)
Affected: 1fcb932c8b5ce86219d7dedcd63659351a43291c , < 2996980e20b7a54a1869df15b3445374b850b155 (git)
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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"
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          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
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              "status": "affected",
              "version": "1fcb932c8b5ce86219d7dedcd63659351a43291c",
              "versionType": "git"
            },
            {
              "lessThan": "2996980e20b7a54a1869df15b3445374b850b155",
              "status": "affected",
              "version": "1fcb932c8b5ce86219d7dedcd63659351a43291c",
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          "programFiles": [
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          "vendor": "Linux",
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              "versionType": "semver"
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              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "6.13",
              "versionType": "original_commit_for_fix"
            }
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        }
      ],
      "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
                }
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      "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",
  "vulnerability-lookup:meta": {
    "epss": {
      "cve": "CVE-2024-56547",
      "date": "2026-09-14",
      "epss": "0.00206",
      "percentile": "0.10762"
    },
    "fkie_nvd": {
      "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.\"}, {\"lang\": \"es\", \"value\": \"En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: rcu/nocb: Corregir la barrera RCU omitida al descargar Actualmente, ejecutar la prueba rcutorture con torture_type=rcu fwd_progress=8 n_barrier_cbs=8 nocbs_nthreads=8 nocbs_toggle=100 onoff_interval=60 test_boost=2, activar\\u00e1 la siguiente advertencia: ADVERTENCIA: CPU: 19 PID: 100 en kernel/rcu/tree_nocb.h:1061 rcu_nocb_rdp_deoffload+0x292/0x2a0 RIP: 0010:rcu_nocb_rdp_deoffload+0x292/0x2a0 Rastreo de llamadas:  ? __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  CPU0 CPU2 CPU3 //rcu_nocb_toggle //nocb_cb_wait //rcutorture // desconecta la CPU1 // procesa el rdp de la CPU1 rcu_barrier() rcu_segcblist_entrain() rcu_segcblist_add_len(1); // len == 2 // poner en cola la barrera // devoluci\\u00f3n de llamada a rdp-\u0026gt;cblist de CPU1 rcu_do_batch() // invocar rdp-\u0026gt;cblist de CPU1 // devoluci\\u00f3n de llamada rcu_barrier_callback() rcu_barrier() mutex_lock(\u0026amp;rcu_state.barrier_mutex); // todav\\u00eda se ve len == 2 // poner en cola la barrera // devoluci\\u00f3n de llamada a rdp-\u0026gt;cblist de CPU1 rcu_segcblist_entrain() rcu_segcblist_add_len(1); // len == 3 // decrementar len rcu_segcblist_add_len(-2); kthread_parkme() // rdp-\u0026gt;cblist de CPU1 len == 1 // Advertir porque todav\\u00eda hay una barrera pendiente // activar la advertencia WARN_ON_ONCE(rcu_segcblist_n_cbs(\u0026amp;rdp-\u0026gt;cblist)); cpus_read_unlock(); // esperar a que la CPU1 se conecte e // invocar la devoluci\\u00f3n de llamada de barrera en // la CPU1 rdp\u0027s-\u0026gt;cblist wait_for_completion(\u0026amp;rcu_state.barrier_completion); // descargar la CPU4 cpus_read_lock() rcu_barrier() mutex_lock(\u0026amp;rcu_state.barrier_mutex); // bloquear en barrier_mutex // esperar a que rcu_barrier() en // la CPU3 desbloquee barrier_mutex // pero la CPU3 desbloquea barrier_mutex // necesita esperar a que la CPU1 se conecte // cuando la CPU1 se conecte se bloquear\\u00e1 en cpus_write_lock El escenario anterior no solo activar\\u00e1 un WARN_ON_ONCE(), sino que tambi\\u00e9n activar\\u00e1 un bloqueo. Gracias al bloqueo de nocb, un segundo rcu_barrier() en una CPU fuera de l\\u00ednea observar\\u00e1 el contador de devoluci\\u00f3n de llamadas reducido a 0 y ahorrar\\u00e1 la puesta en cola de devoluci\\u00f3n de llamadas, o rcuo observar\\u00e1 la nueva devoluci\\u00f3n de llamada y mantendr\\u00e1 rdp-\u0026gt;nocb_cb_sleep en falso. Por lo tanto, verifique rdp-\u0026gt;nocb_cb_sleep antes de estacionar para asegurarse de que no haya m\\u00e1s rcu_barrier() esperando en el rdp.\"}]",
      "id": "CVE-2024-56547",
      "lastModified": "2024-12-27T14:15:34.497",
      "published": "2024-12-27T14:15:34.497",
      "references": "[{\"url\": \"https://git.kernel.org/stable/c/224b62028959858294789772d372dcb36cf5f820\", \"source\": \"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"}, {\"url\": \"https://git.kernel.org/stable/c/2996980e20b7a54a1869df15b3445374b850b155\", \"source\": \"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"}]",
      "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "vulnStatus": "Awaiting Analysis"
    },
    "nvd": "{\"cve\":{\"id\":\"CVE-2024-56547\",\"sourceIdentifier\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"published\":\"2024-12-27T14:15:34.497\",\"lastModified\":\"2026-06-17T08:12:21.670\",\"vulnStatus\":\"Analyzed\",\"cveTags\":[],\"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.\"},{\"lang\":\"es\",\"value\":\"En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: rcu/nocb: Corregir la barrera RCU omitida al descargar Actualmente, ejecutar la prueba rcutorture con torture_type=rcu fwd_progress=8 n_barrier_cbs=8 nocbs_nthreads=8 nocbs_toggle=100 onoff_interval=60 test_boost=2, activar\u00e1 la siguiente advertencia: ADVERTENCIA: CPU: 19 PID: 100 en kernel/rcu/tree_nocb.h:1061 rcu_nocb_rdp_deoffload+0x292/0x2a0 RIP: 0010:rcu_nocb_rdp_deoffload+0x292/0x2a0 Rastreo de llamadas:  ? __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  CPU0 CPU2 CPU3 //rcu_nocb_toggle //nocb_cb_wait //rcutorture // desconecta la CPU1 // procesa el rdp de la CPU1 rcu_barrier() rcu_segcblist_entrain() rcu_segcblist_add_len(1); // len == 2 // poner en cola la barrera // devoluci\u00f3n de llamada a rdp-\u0026gt;cblist de CPU1 rcu_do_batch() // invocar rdp-\u0026gt;cblist de CPU1 // devoluci\u00f3n de llamada rcu_barrier_callback() rcu_barrier() mutex_lock(\u0026amp;rcu_state.barrier_mutex); // todav\u00eda se ve len == 2 // poner en cola la barrera // devoluci\u00f3n de llamada a rdp-\u0026gt;cblist de CPU1 rcu_segcblist_entrain() rcu_segcblist_add_len(1); // len == 3 // decrementar len rcu_segcblist_add_len(-2); kthread_parkme() // rdp-\u0026gt;cblist de CPU1 len == 1 // Advertir porque todav\u00eda hay una barrera pendiente // activar la advertencia WARN_ON_ONCE(rcu_segcblist_n_cbs(\u0026amp;rdp-\u0026gt;cblist)); cpus_read_unlock(); // esperar a que la CPU1 se conecte e // invocar la devoluci\u00f3n de llamada de barrera en // la CPU1 rdp\u0027s-\u0026gt;cblist wait_for_completion(\u0026amp;rcu_state.barrier_completion); // descargar la CPU4 cpus_read_lock() rcu_barrier() mutex_lock(\u0026amp;rcu_state.barrier_mutex); // bloquear en barrier_mutex // esperar a que rcu_barrier() en // la CPU3 desbloquee barrier_mutex // pero la CPU3 desbloquea barrier_mutex // necesita esperar a que la CPU1 se conecte // cuando la CPU1 se conecte se bloquear\u00e1 en cpus_write_lock El escenario anterior no solo activar\u00e1 un WARN_ON_ONCE(), sino que tambi\u00e9n activar\u00e1 un bloqueo. Gracias al bloqueo de nocb, un segundo rcu_barrier() en una CPU fuera de l\u00ednea observar\u00e1 el contador de devoluci\u00f3n de llamadas reducido a 0 y ahorrar\u00e1 la puesta en cola de devoluci\u00f3n de llamadas, o rcuo observar\u00e1 la nueva devoluci\u00f3n de llamada y mantendr\u00e1 rdp-\u0026gt;nocb_cb_sleep en falso. Por lo tanto, verifique rdp-\u0026gt;nocb_cb_sleep antes de estacionar para asegurarse de que no haya m\u00e1s rcu_barrier() esperando en el rdp.\"}],\"affected\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"affectedData\":[{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"unaffected\",\"programFiles\":[\"kernel/rcu/tree_nocb.h\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"1fcb932c8b5ce86219d7dedcd63659351a43291c\",\"lessThan\":\"224b62028959858294789772d372dcb36cf5f820\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"1fcb932c8b5ce86219d7dedcd63659351a43291c\",\"lessThan\":\"2996980e20b7a54a1869df15b3445374b850b155\",\"versionType\":\"git\",\"status\":\"affected\"}]},{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"affected\",\"programFiles\":[\"kernel/rcu/tree_nocb.h\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"6.12\",\"status\":\"affected\"},{\"version\":\"0\",\"lessThan\":\"6.12\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.12.2\",\"lessThanOrEqual\":\"6.12.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.13\",\"lessThanOrEqual\":\"*\",\"versionType\":\"original_commit_for_fix\",\"status\":\"unaffected\"}]}]}],\"metrics\":{\"cvssMetricV31\":[{\"source\":\"nvd@nist.gov\",\"type\":\"Primary\",\"cvssData\":{\"version\":\"3.1\",\"vectorString\":\"CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H\",\"baseScore\":4.7,\"baseSeverity\":\"MEDIUM\",\"attackVector\":\"LOCAL\",\"attackComplexity\":\"HIGH\",\"privilegesRequired\":\"LOW\",\"userInteraction\":\"NONE\",\"scope\":\"UNCHANGED\",\"confidentialityImpact\":\"NONE\",\"integrityImpact\":\"NONE\",\"availabilityImpact\":\"HIGH\"},\"exploitabilityScore\":1.0,\"impactScore\":3.6}]},\"weaknesses\":[{\"source\":\"nvd@nist.gov\",\"type\":\"Primary\",\"description\":[{\"lang\":\"en\",\"value\":\"NVD-CWE-noinfo\"}]}],\"configurations\":[{\"nodes\":[{\"operator\":\"OR\",\"negate\":false,\"cpeMatch\":[{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"6.12\",\"versionEndExcluding\":\"6.12.2\",\"matchCriteriaId\":\"D8882B1B-2ABC-4838-AC1D-DBDBB5764776\"}]}]}],\"references\":[{\"url\":\"https://git.kernel.org/stable/c/224b62028959858294789772d372dcb36cf5f820\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]},{\"url\":\"https://git.kernel.org/stable/c/2996980e20b7a54a1869df15b3445374b850b155\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]}]}}",
    "redhat_vex": {
      "aggregate_severity": "Moderate",
      "current_release_date": "2026-06-28T08:16:18+00:00",
      "cve": "CVE-2024-56547",
      "id": "CVE-2024-56547",
      "initial_release_date": "2024-12-27T00:00:00+00:00",
      "product_status:fixed": "307",
      "product_status:known_affected": "76",
      "product_status:known_not_affected": "198",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: rcu/nocb: Fix missed RCU barrier on deoffloading",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2024/cve-2024-56547.json",
      "version": "3"
    },
    "suse_vex": {
      "aggregate_severity": "moderate",
      "current_release_date": "2026-08-31T13:51:03Z",
      "cve": "CVE-2024-56547",
      "id": "CVE-2024-56547",
      "initial_release_date": "2024-12-28T03:49:06Z",
      "product_status:known_not_affected": "547",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2024-56547",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2024-56547.json",
      "version": "19"
    }
  }
}



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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

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  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
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  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • 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.


Detection rules are retrieved from Rulezet.