CVE-2026-46066

Full vulnerability record from the local CVENow database.

Description

In the Linux kernel, the following vulnerability has been resolved: ceph: fix num_ops off-by-one when crypto allocation fails move_dirty_folio_in_page_array() may fail if the file is encrypted, the dirty folio is not the first in the batch, and it fails to allocate a bounce buffer to hold the ciphertext. When that happens, ceph_process_folio_batch() simply redirties the folio and flushes the current batch -- it can retry that folio in a future batch. However, if this failed folio is not contiguous with the last folio that did make it into the batch, then ceph_process_folio_batch() has already incremented `ceph_wbc->num_ops`; because it doesn't follow through and add the discontiguous folio to the array, ceph_submit_write() -- which expects that `ceph_wbc->num_ops` accurately reflects the number of contiguous ranges (and therefore the required number of "write extent" ops) in the writeback -- will panic the kernel: BUG_ON(ceph_wbc->op_idx + 1 != req->r_num_ops); This issue can be reproduced on affected kernels by writing to fscrypt-enabled CephFS file(s) with a 4KiB-written/4KiB-skipped/repeat pattern (total filesize should not matter) and gradually increasing the system's memory pressure until a bounce buffer allocation fails. Fix this crash by decrementing `ceph_wbc->num_ops` back to the correct value when move_dirty_folio_in_page_array() fails, but the folio already started counting a new (i.e. still-empty) extent. The defect corrected by this patch has existed since 2022 (see first `Fixes:`), but another bug blocked multi-folio encrypted writeback until recently (see second `Fixes:`). The second commit made it into 6.18.16, 6.19.6, and 7.0-rc1, unmasking the panic in those versions. This patch therefore fixes a regression (panic) introduced by cac190c7674f.

Severity

MEDIUM

CVSS score

5.5 (v3.1)

Vulnerability status

Undergoing Analysis

Source identifier

416baaa9-dc9f-4396-8d5f-8c081fb06d67

Published

2026-05-27 14:17:27.320000

Last modified

2026-10-21 13:19:03.003000

View original CVE JSON

{
  "id": "CVE-2026-46066",
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "published": "2026-05-27T14:17:27.320",
  "lastModified": "2026-10-21T13:19:03.003",
  "vulnStatus": "Undergoing Analysis",
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nceph: fix num_ops off-by-one when crypto allocation fails\n\nmove_dirty_folio_in_page_array() may fail if the file is encrypted, the\ndirty folio is not the first in the batch, and it fails to allocate a\nbounce buffer to hold the ciphertext. When that happens,\nceph_process_folio_batch() simply redirties the folio and flushes the\ncurrent batch -- it can retry that folio in a future batch.\n\nHowever, if this failed folio is not contiguous with the last folio that\ndid make it into the batch, then ceph_process_folio_batch() has already\nincremented `ceph_wbc->num_ops`; because it doesn't follow through and\nadd the discontiguous folio to the array, ceph_submit_write() -- which\nexpects that `ceph_wbc->num_ops` accurately reflects the number of\ncontiguous ranges (and therefore the required number of \"write extent\"\nops) in the writeback -- will panic the kernel:\n\n    BUG_ON(ceph_wbc->op_idx + 1 != req->r_num_ops);\n\nThis issue can be reproduced on affected kernels by writing to\nfscrypt-enabled CephFS file(s) with a 4KiB-written/4KiB-skipped/repeat\npattern (total filesize should not matter) and gradually increasing the\nsystem's memory pressure until a bounce buffer allocation fails.\n\nFix this crash by decrementing `ceph_wbc->num_ops` back to the correct\nvalue when move_dirty_folio_in_page_array() fails, but the folio already\nstarted counting a new (i.e. still-empty) extent.\n\nThe defect corrected by this patch has existed since 2022 (see first\n`Fixes:`), but another bug blocked multi-folio encrypted writeback until\nrecently (see second `Fixes:`). The second commit made it into 6.18.16,\n6.19.6, and 7.0-rc1, unmasking the panic in those versions. This patch\ntherefore fixes a regression (panic) introduced by cac190c7674f."
    }
  ],
  "affected": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "affectedData": [
        {
          "vendor": "Linux",
          "product": "Linux",
          "defaultStatus": "unaffected",
          "programFiles": [
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          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
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              "versionType": "git",
              "status": "affected"
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              "versionType": "git",
              "status": "affected"
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            {
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        {
          "vendor": "Linux",
          "product": "Linux",
          "defaultStatus": "affected",
          "programFiles": [
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          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "versions": [
            {
              "version": "6.6",
              "status": "affected"
            },
            {
              "version": "0",
              "lessThan": "6.6",
              "versionType": "semver",
              "status": "unaffected"
            },
            {
              "version": "6.6.160",
              "lessThanOrEqual": "6.6.*",
              "versionType": "semver",
              "status": "unaffected"
            },
            {
              "version": "6.12.114",
              "lessThanOrEqual": "6.12.*",
              "versionType": "semver",
              "status": "unaffected"
            },
            {
              "version": "6.18.30",
              "lessThanOrEqual": "6.18.*",
              "versionType": "semver",
              "status": "unaffected"
            },
            {
              "version": "7.0.4",
              "lessThanOrEqual": "7.0.*",
              "versionType": "semver",
              "status": "unaffected"
            },
            {
              "version": "7.1",
              "lessThanOrEqual": "*",
              "versionType": "original_commit_for_fix",
              "status": "unaffected"
            }
          ]
        }
      ]
    }
  ],
  "metrics": {
    "cvssMetricV31": [
      {
        "source": "[email protected]",
        "type": "Primary",
        "cvssData": {
          "version": "3.1",
          "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
          "baseScore": 5.5,
          "baseSeverity": "MEDIUM",
          "attackVector": "LOCAL",
          "attackComplexity": "LOW",
          "privilegesRequired": "LOW",
          "userInteraction": "NONE",
          "scope": "UNCHANGED",
          "confidentialityImpact": "NONE",
          "integrityImpact": "NONE",
          "availabilityImpact": "HIGH"
        },
        "exploitabilityScore": 1.8,
        "impactScore": 3.6
      }
    ]
  },
  "weaknesses": [
    {
      "source": "[email protected]",
      "type": "Primary",
      "description": [
        {
          "lang": "en",
          "value": "CWE-193"
        }
      ]
    }
  ],
  "configurations": [
    {
      "nodes": [
        {
          "operator": "OR",
          "negate": false,
          "cpeMatch": [
            {
              "vulnerable": true,
              "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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  "references": [
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}