{
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        "title": "CVE Program Container"
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              "content": {
                "id": "CVE-2021-47178",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "partial"
                  }
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                "role": "CISA Coordinator",
                "timestamp": "2024-09-10T15:54:21.876109Z",
                "version": "2.0.3"
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          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "drivers/target/target_core_transport.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
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              "lessThan": "a222d2794c53f8165de20aa91b39e35e4b72bce9",
              "status": "affected",
              "version": "008b936bbde3e87a611b3828a0d5d2a4f99026a0",
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          "product": "Linux",
          "programFiles": [
            "drivers/target/target_core_transport.c"
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          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "5.11"
            },
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              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
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            {
              "lessThanOrEqual": "5.12.*",
              "status": "unaffected",
              "version": "5.12.9",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "5.13",
              "versionType": "original_commit_for_fix"
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          ]
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                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "5.12.9",
                  "versionStartIncluding": "5.11",
                  "vulnerable": true
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                {
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      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nscsi: target: core: Avoid smp_processor_id() in preemptible code\n\nThe BUG message \"BUG: using smp_processor_id() in preemptible [00000000]\ncode\" was observed for TCMU devices with kernel config DEBUG_PREEMPT.\n\nThe message was observed when blktests block/005 was run on TCMU devices\nwith fileio backend or user:zbc backend [1]. The commit 1130b499b4a7\n(\"scsi: target: tcm_loop: Use LIO wq cmd submission helper\") triggered the\nsymptom. The commit modified work queue to handle commands and changed\n\u0027current-\u003enr_cpu_allowed\u0027 at smp_processor_id() call.\n\nThe message was also observed at system shutdown when TCMU devices were not\ncleaned up [2]. The function smp_processor_id() was called in SCSI host\nwork queue for abort handling, and triggered the BUG message. This symptom\nwas observed regardless of the commit 1130b499b4a7 (\"scsi: target:\ntcm_loop: Use LIO wq cmd submission helper\").\n\nTo avoid the preemptible code check at smp_processor_id(), get CPU ID with\nraw_smp_processor_id() instead. The CPU ID is used for performance\nimprovement then thread move to other CPU will not affect the code.\n\n[1]\n\n[   56.468103] run blktests block/005 at 2021-05-12 14:16:38\n[   57.369473] check_preemption_disabled: 85 callbacks suppressed\n[   57.369480] BUG: using smp_processor_id() in preemptible [00000000] code: fio/1511\n[   57.369506] BUG: using smp_processor_id() in preemptible [00000000] code: fio/1510\n[   57.369512] BUG: using smp_processor_id() in preemptible [00000000] code: fio/1506\n[   57.369552] caller is __target_init_cmd+0x157/0x170 [target_core_mod]\n[   57.369606] CPU: 4 PID: 1506 Comm: fio Not tainted 5.13.0-rc1+ #34\n[   57.369613] Hardware name: System manufacturer System Product Name/PRIME Z270-A, BIOS 1302 03/15/2018\n[   57.369617] Call Trace:\n[   57.369621] BUG: using smp_processor_id() in preemptible [00000000] code: fio/1507\n[   57.369628]  dump_stack+0x6d/0x89\n[   57.369642]  check_preemption_disabled+0xc8/0xd0\n[   57.369628] caller is __target_init_cmd+0x157/0x170 [target_core_mod]\n[   57.369655]  __target_init_cmd+0x157/0x170 [target_core_mod]\n[   57.369695]  target_init_cmd+0x76/0x90 [target_core_mod]\n[   57.369732]  tcm_loop_queuecommand+0x109/0x210 [tcm_loop]\n[   57.369744]  scsi_queue_rq+0x38e/0xc40\n[   57.369761]  __blk_mq_try_issue_directly+0x109/0x1c0\n[   57.369779]  blk_mq_try_issue_directly+0x43/0x90\n[   57.369790]  blk_mq_submit_bio+0x4e5/0x5d0\n[   57.369812]  submit_bio_noacct+0x46e/0x4e0\n[   57.369830]  __blkdev_direct_IO_simple+0x1a3/0x2d0\n[   57.369859]  ? set_init_blocksize.isra.0+0x60/0x60\n[   57.369880]  generic_file_read_iter+0x89/0x160\n[   57.369898]  blkdev_read_iter+0x44/0x60\n[   57.369906]  new_sync_read+0x102/0x170\n[   57.369929]  vfs_read+0xd4/0x160\n[   57.369941]  __x64_sys_pread64+0x6e/0xa0\n[   57.369946]  ? lockdep_hardirqs_on+0x79/0x100\n[   57.369958]  do_syscall_64+0x3a/0x70\n[   57.369965]  entry_SYSCALL_64_after_hwframe+0x44/0xae\n[   57.369973] RIP: 0033:0x7f7ed4c1399f\n[   57.369979] Code: 08 89 3c 24 48 89 4c 24 18 e8 7d f3 ff ff 4c 8b 54 24 18 48 8b 54 24 10 41 89 c0 48 8b 74 24 08 8b 3c 24 b8 11 00 00 00 0f 05 \u003c48\u003e 3d 00 f0 ff ff 77 31 44 89 c7 48 89 04 24 e8 cd f3 ff ff 48 8b\n[   57.369983] RSP: 002b:00007ffd7918c580 EFLAGS: 00000293 ORIG_RAX: 0000000000000011\n[   57.369990] RAX: ffffffffffffffda RBX: 00000000015b4540 RCX: 00007f7ed4c1399f\n[   57.369993] RDX: 0000000000001000 RSI: 00000000015de000 RDI: 0000000000000009\n[   57.369996] RBP: 00000000015b4540 R08: 0000000000000000 R09: 0000000000000001\n[   57.369999] R10: 0000000000e5c000 R11: 0000000000000293 R12: 00007f7eb5269a70\n[   57.370002] R13: 0000000000000000 R14: 0000000000001000 R15: 00000000015b4568\n[   57.370031] CPU: 7 PID: 1507 Comm: fio Not tainted 5.13.0-rc1+ #34\n[   57.370036] Hardware name: System manufacturer System Product Name/PRIME Z270-A, BIOS 1302 03/15/2018\n[   57.370039] Call Trace:\n[   57.370045]  dump_stack+0x6d/0x89\n[   57.370056]  ch\n---truncated---"
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 7.5,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:N - __target_init_cmd() is shared target-core code invoked from network fabrics including iSCSI (iscsit_setup_scsi_cmd/iscsit_handle_task_mgt_cmd) on every SCSI/TMF PDU after session setup; an internet-facing or LAN iSCSI target is the primary deployment of this subsystem.\nAC:L - Every command initialization in preemptible context deterministically hits smp_processor_id()\u0027s DEBUG_PREEMPT check with no race or attacker-uncontrollable memory layout; the attacker fully controls command rate over an established session.\nPR:N - iSCSI commonly runs with authentication disabled (AuthMethod=None / authentication=0) and open ACLs, so a remote initiator can complete login and send SCSI commands with no credentials on the target host.\nUI:N - The attacker triggers the path by sending their own iSCSI SCSI/TMF PDUs; no separate victim action such as mounting or opening a file is required.\nS:U - Impact stays inside the host kernel target-core path under the same OS security authority, with no VM escape, IOMMU bypass, or sandbox boundary crossing.\nC:N - check_preemption_disabled() only emits a rate-limited symbolic dump_stack(); smp_processor_id() still returns a valid CPU id with no OOB/UAF read, and the commit states CPU affinity is performance-only.\nI:N - raw_smp_processor_id() has identical value semantics for this snapshot use; cmd-\u003ecpuid only selects a per-CPU state_list/workqueue affinity hint and creates no write, corruption, or control-flow hijack primitive.\nA:H - The defect fires on the SCSI command hot path and emits a kernel BUG: report with full dump_stack() that a remote initiator can drive repeatedly, producing a sustained log/console printk storm that can stall I/O (matching hot-path DEBUG_PREEMPT SCSI precedent)."
            }
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      "providerMetadata": {
        "dateUpdated": "2026-08-05T08:46:30.525Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
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      "references": [
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          "url": "https://git.kernel.org/stable/c/a222d2794c53f8165de20aa91b39e35e4b72bce9"
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          "url": "https://git.kernel.org/stable/c/a20b6eaf4f35046a429cde57bee7eb5f13d6857f"
        },
        {
          "url": "https://git.kernel.org/stable/c/70ca3c57ff914113f681e657634f7fbfa68e1ad1"
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      "title": "scsi: target: core: Avoid smp_processor_id() in preemptible code",
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  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2021-47178",
    "datePublished": "2024-03-25T09:16:28.024Z",
    "dateReserved": "2024-03-25T09:12:14.112Z",
    "dateUpdated": "2026-08-05T08:46:30.525Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}