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dm-thin: fix metadata refcount underflow

Type: advisorySource: Official CVE List1 source record

In the Linux kernel, the following vulnerability has been resolved: dm-thin: fix metadata refcount underflow There's a bug in dm-thin in the function rebalance_children. If the internal btree node has one entry, the code tries to copy all btree entries from the node's child to the node itself and then decrement the child's reference count. If the child node is shared (it has reference count > 1), we won't free it, so there would be two pointers to each of the grandchildren nodes. But the reference counts of the grandchildren is not increased, thus the reference count doesn't match the number of pointers that point to the grandchildren. This results in "device mapper: space map common: unable to decrement block" errors. Fix this bug by incrementing reference counts on the grandchildren if the btree node is shared.

Announced Source revision 1
Original source ↗

CVE-2026-46107

Primary source · Revision 1

Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.

Security context

Source reference: cve:CVE-2026-46107

Linux

Source reference: /containers/cna/affected/0/product

Affected versions
Not stated in this record
Fixed versions
Not stated in this record
Prerequisites
Not stated in this record

Linux

Source reference: /containers/cna/affected/1/product

Affected versions
Not stated in this record
Fixed versions
Not stated in this record
Prerequisites
Not stated in this record

Structured affected-version data

Original package identities and version rules from this source.

[
  {
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "vendor": "Linux",
    "product": "Linux",
    "versions": [
      {
        "status": "affected",
        "version": "3241b1d3e0aaafbfcd320f4d71ade629728cc4f4",
        "lessThan": "b719d12cb94df345e9ad2715fd0abe9afcaeb111",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "3241b1d3e0aaafbfcd320f4d71ade629728cc4f4",
        "lessThan": "f49b41c9eb7c6ff00df27cd49cea210abbadd8ad",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "3241b1d3e0aaafbfcd320f4d71ade629728cc4f4",
        "lessThan": "f06f6aededd792a754cd677c02b3d3016d868c2c",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "3241b1d3e0aaafbfcd320f4d71ade629728cc4f4",
        "lessThan": "12161e03d33afce781f68fa11cc6060538862fad",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "3241b1d3e0aaafbfcd320f4d71ade629728cc4f4",
        "lessThan": "323d252a4a378834e4fe68298ca61cfc5dd3a460",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "3241b1d3e0aaafbfcd320f4d71ade629728cc4f4",
        "lessThan": "85311a585a26640760cd0f3349ab9f2905691044",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "3241b1d3e0aaafbfcd320f4d71ade629728cc4f4",
        "lessThan": "5ec0debbcfd43596e32c1239e993de06a704e04c",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "3241b1d3e0aaafbfcd320f4d71ade629728cc4f4",
        "lessThan": "09a65adc7d8bbfce06392cb6d375468e2728ead5",
        "versionType": "git"
      }
    ],
    "programFiles": [
      "drivers/md/persistent-data/dm-btree-remove.c"
    ],
    "defaultStatus": "unaffected"
  },
  {
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "vendor": "Linux",
    "product": "Linux",
    "versions": [
      {
        "status": "affected",
        "version": "3.2"
      },
      {
        "status": "unaffected",
        "version": "0",
        "lessThan": "3.2",
        "versionType": "semver"
      },
      {
        "status": "unaffected",
        "version": "5.10.259",
        "versionType": "semver",
        "lessThanOrEqual": "5.10.*"
      },
      {
        "status": "unaffected",
        "version": "5.15.209",
        "versionType": "semver",
        "lessThanOrEqual": "5.15.*"
      },
      {
        "status": "unaffected",
        "version": "6.1.175",
        "versionType": "semver",
        "lessThanOrEqual": "6.1.*"
      },
      {
        "status": "unaffected",
        "version": "6.6.140",
        "versionType": "semver",
        "lessThanOrEqual": "6.6.*"
      },
      {
        "status": "unaffected",
        "version": "6.12.88",
        "versionType": "semver",
        "lessThanOrEqual": "6.12.*"
      },
      {
        "status": "unaffected",
        "version": "6.18.30",
        "versionType": "semver",
        "lessThanOrEqual": "6.18.*"
      },
      {
        "status": "unaffected",
        "version": "7.0.7",
        "versionType": "semver",
        "lessThanOrEqual": "7.0.*"
      },
      {
        "status": "unaffected",
        "version": "7.1",
        "versionType": "original_commit_for_fix",
        "lessThanOrEqual": "*"
      }
    ],
    "programFiles": [
      "drivers/md/persistent-data/dm-btree-remove.c"
    ],
    "defaultStatus": "affected"
  }
]
Related CVEs
CVE-2026-46107

Source reference: /cveMetadata/cveId

Publisher severity

high

Source reference: /containers/cna/metrics

Event
#40118 · Revision 1
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Publisher date
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