cve-2024-56547
Vulnerability from cvelistv5
Published
2024-12-27 14:11
Modified
2025-01-20 06:22
Severity ?
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.
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/224b62028959858294789772d372dcb36cf5f820
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/2996980e20b7a54a1869df15b3445374b850b155
Impacted products
Vendor Product Version
Linux Linux Version: 1fcb932c8b5ce86219d7dedcd63659351a43291c
Version: 1fcb932c8b5ce86219d7dedcd63659351a43291c
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   Linux Linux Version: 6.12
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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",
                  },
               ],
            },
         ],
         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  <TASK>\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  </TASK>\n\nCPU0                               CPU2                          CPU3\n//rcu_nocb_toggle             //nocb_cb_wait                   //rcutorture\n\n// deoffload CPU1             // process CPU1's rdp\nrcu_barrier()\n    rcu_segcblist_entrain()\n        rcu_segcblist_add_len(1);\n        // len == 2\n        // enqueue barrier\n        // callback to CPU1's\n        // rdp->cblist\n                             rcu_do_batch()\n                                 // invoke CPU1's rdp->cblist\n                                 // callback\n                                 rcu_barrier_callback()\n                                                             rcu_barrier()\n                                                               mutex_lock(&rcu_state.barrier_mutex);\n                                                               // still see len == 2\n                                                               // enqueue barrier callback\n                                                               // to CPU1's rdp->cblist\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's rdp->cblist len == 1\n// Warn because there is\n// still a pending barrier\n// trigger warning\nWARN_ON_ONCE(rcu_segcblist_n_cbs(&rdp->cblist));\ncpus_read_unlock();\n\n                                                                // wait CPU1 to comes online and\n                                                                // invoke barrier callback on\n                                                                // CPU1 rdp's->cblist\n                                                                wait_for_completion(&rcu_state.barrier_completion);\n// deoffload CPU4\ncpus_read_lock()\n  rcu_barrier()\n    mutex_lock(&rcu_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->nocb_cb_sleep to false.\n\nTherefore check rdp->nocb_cb_sleep before parking to make sure no\nfurther rcu_barrier() is waiting on the rdp.",
            },
         ],
         providerMetadata: {
            dateUpdated: "2025-01-20T06:22:40.140Z",
            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-5f407fcff5a0",
         },
      },
   },
   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: "2025-01-20T06:22:40.140Z",
      state: "PUBLISHED",
   },
   dataType: "CVE_RECORD",
   dataVersion: "5.1",
   "vulnerability-lookup:meta": {
      nvd: "{\"cve\":{\"id\":\"CVE-2024-56547\",\"sourceIdentifier\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"published\":\"2024-12-27T14:15:34.497\",\"lastModified\":\"2024-12-27T14:15:34.497\",\"vulnStatus\":\"Received\",\"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  <TASK>\\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  </TASK>\\n\\nCPU0                               CPU2                          CPU3\\n//rcu_nocb_toggle             //nocb_cb_wait                   //rcutorture\\n\\n// deoffload CPU1             // process CPU1's rdp\\nrcu_barrier()\\n    rcu_segcblist_entrain()\\n        rcu_segcblist_add_len(1);\\n        // len == 2\\n        // enqueue barrier\\n        // callback to CPU1's\\n        // rdp->cblist\\n                             rcu_do_batch()\\n                                 // invoke CPU1's rdp->cblist\\n                                 // callback\\n                                 rcu_barrier_callback()\\n                                                             rcu_barrier()\\n                                                               mutex_lock(&rcu_state.barrier_mutex);\\n                                                               // still see len == 2\\n                                                               // enqueue barrier callback\\n                                                               // to CPU1's rdp->cblist\\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's rdp->cblist len == 1\\n// Warn because there is\\n// still a pending barrier\\n// trigger warning\\nWARN_ON_ONCE(rcu_segcblist_n_cbs(&rdp->cblist));\\ncpus_read_unlock();\\n\\n                                                                // wait CPU1 to comes online and\\n                                                                // invoke barrier callback on\\n                                                                // CPU1 rdp's->cblist\\n                                                                wait_for_completion(&rcu_state.barrier_completion);\\n// deoffload CPU4\\ncpus_read_lock()\\n  rcu_barrier()\\n    mutex_lock(&rcu_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->nocb_cb_sleep to false.\\n\\nTherefore check rdp->nocb_cb_sleep before parking to make sure no\\nfurther rcu_barrier() is waiting on the rdp.\"}],\"metrics\":{},\"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\"}]}}",
   },
}


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