FKIE_CVE-2026-72420

Vulnerability from fkie_nvd - Published: 2026-08-15 06:22 - Updated: 2026-10-16 19:17
Severity
8.8 (High) - CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: md/raid5: avoid R5_Overlap races while breaking stripe batches KCSAN report a race in break_stripe_batch_list() vs. raid5_make_request() on sh->dev[i].flags (plain word write vs. atomic bit op).. and .. one possible scenario is: CPU1 CPU2 break_stripe_batch_list(sh1) -> handle sh2 -> lock(sh2) -> sh2->batch_head = NULL -> unlock(sh2) -> test_and_clear_bit(R5_Overlap, sh2->dev[i].flags) -> wake_up_bit(sh2->dev[i].flags) raid5_make_request() -> add_all_stripe_bios(sh2) -> lock(sh2) -> stripe_bio_overlaps(sh2) returns true batch_head is NULL, so new bio overlap exist bio on sh2 -> true -> set_bit(R5_Overlap, sh2->dev[i].flags) -> unlock(sh2) -> wait_on_bit(sh2->dev[i].flags) -> sh2->dev[i].flags = sh1->dev[i].flags & ~R5_Overlap No wait_up_bit(), CPU2 could be wait_on_bit() forever... Fix by : - Expand the protect zone. - Use batch_head's device flag's snaphot when no held head_sh->stripe_lock. - Move sh/head_sh->batch_head = NULL to the end of protected zone , and , any concurrent add_all_stripe_bios() grabs sh->stripe_lock now either: - see batch_head != null, and , is rejected by stripe_bio_overlaps() under the lock (no R5_Overlap wait ) , or , - sees batch_head == NULL, only after dev[i].flags has already been set and the prior R5_Overlap waiters worken. KCSAN report: ================================================ BUG: KCSAN: data-race in break_stripe_batch_list / raid5_make_request write (marked) to 0xffff8e89c8117548 of 8 bytes by task 4042 on cpu 0: raid5_make_request+0xea0/0x2930 md_handle_request+0x4a2/0xa40 md_submit_bio+0x109/0x1a0 __submit_bio+0x2ec/0x390 submit_bio_noacct_nocheck+0x457/0x710 submit_bio_noacct+0x2a7/0xc20 submit_bio+0x56/0x250 blkdev_direct_IO+0x54c/0xda0 blkdev_write_iter+0x38f/0x570 aio_write+0x22b/0x490 io_submit_one+0xa51/0xf70 __x64_sys_io_submit+0xf7/0x220 x64_sys_call+0x1907/0x1c60 do_syscall_64+0x130/0x570 entry_SYSCALL_64_after_hwframe+0x76/0x7e read to 0xffff8e89c8117548 of 8 bytes by task 4010 on cpu 5: break_stripe_batch_list+0x249/0x480 handle_stripe_clean_event+0x720/0x9b0 handle_stripe+0x32fb/0x4500 handle_active_stripes.isra.0+0x6e0/0xa50 raid5d+0x7e0/0xba0 md_thread+0x15a/0x2d0 kthread+0x1e3/0x220 ret_from_fork+0x37a/0x410 ret_from_fork_asm+0x1a/0x30 value changed: 0x0000000000000019 -> 0x0000000000000099 --> R5_Overlap
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/4d919c9b770996365806b6c8d701912d52baa306
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/55b77337bdd088c77461588e5ec094421b89911b
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/8031b0d02bd221a5f9add4357e291fc2a527b83a
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/d684b72dfbd320623ccaab0779aa841190488e7c
Impacted products
Vendor Product Version
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{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "drivers/md/raid5.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "8031b0d02bd221a5f9add4357e291fc2a527b83a",
              "status": "affected",
              "version": "fb642b92c267beeefd352af9bc461eac93a7552c",
              "versionType": "git"
            },
            {
              "lessThan": "4d919c9b770996365806b6c8d701912d52baa306",
              "status": "affected",
              "version": "fb642b92c267beeefd352af9bc461eac93a7552c",
              "versionType": "git"
            },
            {
              "lessThan": "d684b72dfbd320623ccaab0779aa841190488e7c",
              "status": "affected",
              "version": "fb642b92c267beeefd352af9bc461eac93a7552c",
              "versionType": "git"
            },
            {
              "lessThan": "55b77337bdd088c77461588e5ec094421b89911b",
              "status": "affected",
              "version": "fb642b92c267beeefd352af9bc461eac93a7552c",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "drivers/md/raid5.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "4.1"
            },
            {
              "lessThan": "4.1",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.97",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.40",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.1.*",
              "status": "unaffected",
              "version": "7.1.5",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.2",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nmd/raid5: avoid R5_Overlap races while breaking stripe batches\n\nKCSAN report a race in break_stripe_batch_list() vs. raid5_make_request()\non sh-\u003edev[i].flags (plain word write vs. atomic bit op)..\n\nand .. one possible scenario is:\n\nCPU1                            CPU2\nbreak_stripe_batch_list(sh1)\n-\u003e handle sh2\n-\u003e lock(sh2)\n-\u003e sh2-\u003ebatch_head = NULL\n-\u003e unlock(sh2)\n-\u003e test_and_clear_bit(R5_Overlap, sh2-\u003edev[i].flags)\n-\u003e wake_up_bit(sh2-\u003edev[i].flags)\n                                raid5_make_request()\n                                -\u003e add_all_stripe_bios(sh2)\n                                -\u003e lock(sh2)\n                                -\u003e stripe_bio_overlaps(sh2) returns true\n\t\t\t\t   batch_head is NULL, so new bio overlap\n\t\t\t\t   exist bio on sh2 -\u003e true\n                                -\u003e set_bit(R5_Overlap, sh2-\u003edev[i].flags)\n                                -\u003e unlock(sh2)\n                                -\u003e wait_on_bit(sh2-\u003edev[i].flags)\n-\u003e sh2-\u003edev[i].flags = sh1-\u003edev[i].flags \u0026 ~R5_Overlap\n\nNo wait_up_bit(), CPU2 could be wait_on_bit() forever...\n\nFix by :\n- Expand the protect zone.\n- Use batch_head\u0027s device flag\u0027s snaphot when no held head_sh-\u003estripe_lock.\n- Move sh/head_sh-\u003ebatch_head = NULL to the end of protected zone , and ,\n  any concurrent add_all_stripe_bios() grabs sh-\u003estripe_lock now either:\n\t- see batch_head != null, and , is rejected by stripe_bio_overlaps()\n\t  under the lock (no R5_Overlap wait ) , or ,\n\t- sees batch_head == NULL, only after dev[i].flags has already been\n\t  set and the prior R5_Overlap waiters worken.\n\nKCSAN report:\n================================================\n  BUG: KCSAN: data-race in break_stripe_batch_list / raid5_make_request\n\n  write (marked) to 0xffff8e89c8117548 of 8 bytes by task 4042 on cpu 0:\n    raid5_make_request+0xea0/0x2930\n    md_handle_request+0x4a2/0xa40\n    md_submit_bio+0x109/0x1a0\n    __submit_bio+0x2ec/0x390\n    submit_bio_noacct_nocheck+0x457/0x710\n    submit_bio_noacct+0x2a7/0xc20\n    submit_bio+0x56/0x250\n    blkdev_direct_IO+0x54c/0xda0\n    blkdev_write_iter+0x38f/0x570\n    aio_write+0x22b/0x490\n    io_submit_one+0xa51/0xf70\n    __x64_sys_io_submit+0xf7/0x220\n    x64_sys_call+0x1907/0x1c60\n    do_syscall_64+0x130/0x570\n    entry_SYSCALL_64_after_hwframe+0x76/0x7e\n\n  read to 0xffff8e89c8117548 of 8 bytes by task 4010 on cpu 5:\n    break_stripe_batch_list+0x249/0x480\n    handle_stripe_clean_event+0x720/0x9b0\n    handle_stripe+0x32fb/0x4500\n    handle_active_stripes.isra.0+0x6e0/0xa50\n    raid5d+0x7e0/0xba0\n    md_thread+0x15a/0x2d0\n    kthread+0x1e3/0x220\n    ret_from_fork+0x37a/0x410\n    ret_from_fork_asm+0x1a/0x30\n\n  value changed: 0x0000000000000019 -\u003e 0x0000000000000099 --\u003e R5_Overlap"
    }
  ],
  "id": "CVE-2026-72420",
  "lastModified": "2026-10-16T19:17:29.450",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "NETWORK",
          "availabilityImpact": "HIGH",
          "baseScore": 8.8,
          "baseSeverity": "HIGH",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "HIGH",
          "privilegesRequired": "LOW",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 2.8,
        "impactScore": 5.9,
        "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "type": "Secondary"
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2026-72420",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "no"
            },
            {
              "technicalImpact": "total"
            }
          ],
          "role": "CISA Coordinator",
          "timestamp": "2026-10-16T18:49:28.867554Z",
          "version": "2.0.3"
        }
      }
    ]
  },
  "published": "2026-08-15T06:22:15.743",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/4d919c9b770996365806b6c8d701912d52baa306"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/55b77337bdd088c77461588e5ec094421b89911b"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/8031b0d02bd221a5f9add4357e291fc2a527b83a"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/d684b72dfbd320623ccaab0779aa841190488e7c"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Received"
}



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