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linux — security advisory

Type: advisorySources: OSVAdvisory ID: DEBIAN-CVE-2022-49075

In the Linux kernel, the following vulnerability has been resolved: btrfs: fix qgroup reserve overflow the qgroup limit We use extent_changeset->bytes_changed in qgroup_reserve_data() to record how many bytes we set for EXTENT_QGROUP_RESERVED state. Currently the bytes_changed is set as "unsigned int", and it will overflow if we try to fallocate a range larger than 4GiB. The result is we reserve less bytes and eventually break the qgroup limit. Unlike regular buffered/direct write, which we use one changeset for each ordered extent, which can never be larger than 256M. For fallocate, we use one changeset for the whole range, thus it no longer respects the 256M per extent limit, and caused the problem. The following example test script reproduces the problem: $ cat qgroup-overflow.sh #!/bin/bash DEV=/dev/sdj MNT=/mnt/sdj mkfs.btrfs -f $DEV mount $DEV $MNT # Set qgroup limit to 2GiB. btrfs quota enable $MNT btrfs qgroup limit 2G $MNT # Try to fallocate a 3GiB file. This should fail. echo echo "Try to fallocate a 3GiB file..." fallocate -l 3G $MNT/3G.file # Try to fallocate a 5GiB file. echo echo "Try to fallocate a 5GiB file..." fallocate -l 5G $MNT/5G.file # See we break the qgroup limit. echo sync btrfs qgroup show -r $MNT umount $MNT When running the test: $ ./qgroup-overflow.sh (...) Try to fallocate a 3GiB file... fallocate: fallocate failed: Disk quota exceeded Try to fallocate a 5GiB file... qgroupid rfer excl max_rfer -------- ---- ---- -------- 0/5 5.00GiB 5.00GiB 2.00

Products
linux
Affected versions
Not specified
Fixed versions
5.17.3-1
CVEs
CVE-2022-49075
Confirmed fixed CVEs
Not specified
Updated in this feed
30 Oct 2026, 15:37 UTC · Revision 1

Source evidence

DEBIAN-CVE-2022-49075

core-osv · Original source

Published 26 Feb 2025, 07:00 UTC

In the Linux kernel, the following vulnerability has been resolved: btrfs: fix qgroup reserve overflow the qgroup limit We use extent_changeset->bytes_changed in qgroup_reserve_data() to record how many bytes we set for EXTENT_QGROUP_RESERVED state. Currently the bytes_changed is set as "unsigned int", and it will overflow if we try to fallocate a range larger than 4GiB. The result is we reserve less bytes and eventually break the qgroup limit. Unlike regular buffered/direct write, which we use one changeset for each ordered extent, which can never be larger than 256M. For fallocate, we use one changeset for the whole range, thus it no longer respects the 256M per extent limit, and caused the problem. The following example test script reproduces the problem: $ cat qgroup-overflow.sh #!/bin/bash DEV=/dev/sdj MNT=/mnt/sdj mkfs.btrfs -f $DEV mount $DEV $MNT # Set qgroup limit to 2GiB. btrfs quota enable $MNT btrfs qgroup limit 2G $MNT # Try to fallocate a 3GiB file. This should fail. echo echo "Try to fallocate a 3GiB file..." fallocate -l 3G $MNT/3G.file # Try to fallocate a 5GiB file. echo echo "Try to fallocate a 5GiB file..." fallocate -l 5G $MNT/5G.file # See we break the qgroup limit. echo sync btrfs qgroup show -r $MNT umount $MNT When running the test: $ ./qgroup-overflow.sh (...) Try to fallocate a 3GiB file... fallocate: fallocate failed: Disk quota exceeded Try to fallocate a 5GiB file... qgroupid rfer excl max_rfer -------- ---- ---- -------- 0/5 5.00GiB 5.00GiB 2.00

osv:DEBIAN-CVE-2022-49075

linux

Fixed versions: 5.17.3-1

linux

Fixed versions: 5.17.3-1

linux

Fixed versions: 5.17.3-1

Complete source record
{
  "id": "8fa08e798a07093930ffb6db5fc6baf436e08141ed4ef7bded7cc639db15518b",
  "url": "https://osv.dev/vulnerability/DEBIAN-CVE-2022-49075",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "DEBIAN-CVE-2022-49075",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: btrfs: fix qgroup reserve overflow the qgroup limit We use extent_changeset->bytes_changed in qgroup_reserve_data() to record how many bytes we set for EXTENT_QGROUP_RESERVED state. Currently the bytes_changed is set as \"unsigned int\", and it will overflow if we try to fallocate a range larger than 4GiB. The result is we reserve less bytes and eventually break the qgroup limit. Unlike regular buffered/direct write, which we use one changeset for each ordered extent, which can never be larger than 256M. For fallocate, we use one changeset for the whole range, thus it no longer respects the 256M per extent limit, and caused the problem. The following example test script reproduces the problem: $ cat qgroup-overflow.sh #!/bin/bash DEV=/dev/sdj MNT=/mnt/sdj mkfs.btrfs -f $DEV mount $DEV $MNT # Set qgroup limit to 2GiB. btrfs quota enable $MNT btrfs qgroup limit 2G $MNT # Try to fallocate a 3GiB file. This should fail. echo echo \"Try to fallocate a 3GiB file...\" fallocate -l 3G $MNT/3G.file # Try to fallocate a 5GiB file. echo echo \"Try to fallocate a 5GiB file...\" fallocate -l 5G $MNT/5G.file # See we break the qgroup limit. echo sync btrfs qgroup show -r $MNT umount $MNT When running the test: $ ./qgroup-overflow.sh (...) Try to fallocate a 3GiB file... fallocate: fallocate failed: Disk quota exceeded Try to fallocate a 5GiB file... qgroupid rfer excl max_rfer -------- ---- ---- -------- 0/5 5.00GiB 5.00GiB 2.00",
    "evidence": "osv:DEBIAN-CVE-2022-49075",
    "products": [
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          "evidence": "/affected/0/package/name"
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    "severity": "medium",
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      "aliases": [
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      "metrics": [
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          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H"
        }
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            "ecosystem": "Debian:12"
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            "source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2022-49075.json"
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          "package": {
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            "purl": "pkg:deb/debian/linux?arch=source&distro=trixie",
            "ecosystem": "Debian:13"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2022-49075.json"
          },
          "ecosystem_specific": {
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        {
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      ],
      "modified": "2026-10-15T08:03:10.007086927Z",
      "provider": "osv",
      "upstream": [
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      ],
      "references": [
        "https://security-tracker.debian.org/tracker/CVE-2022-49075"
      ]
    },
    "related_cves": [
      {
        "value": "CVE-2022-49075",
        "evidence": "/upstream"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 325467,
  "published_at": "2025-02-26T07:00:44.847+00:00"
}