# CVE-2022-49075: linux: In the Linux kernel, the following vulnerability has been resolved:  btrfs: fix qgroup reserve overflow the qgroup li...

CVE-2022-49075 is fixed in linux on 1 platform, first by DEBIAN-CVE-2022-49075, released February 26, 2025. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2022-49075
- Priority: Routine
- CVSS: 5.5 (medium)
- EPSS: 0.0067
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Feb 26, 2025

## Description

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      2.00GiB  Since we have no control of how bytes_changed is used, it's better to set it to u64.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | linux Debian 12.15 (bookworm) | 5.17.3-1 | [DEBIAN-CVE-2022-49075](https://patchblox.com/security/data/fix/linux/debian-cve-2022-49075.md) | Feb 26, 2025 |
| Linux | linux Debian 13.5 (trixie) | 5.17.3-1 | [DEBIAN-CVE-2022-49075](https://patchblox.com/security/data/fix/linux/debian-cve-2022-49075.md) | Feb 26, 2025 |
| Linux | linux Debian 14 | 5.17.3-1 | [DEBIAN-CVE-2022-49075](https://patchblox.com/security/data/fix/linux/debian-cve-2022-49075.md) | Feb 26, 2025 |

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Data as of 2026-11-08T00:53:09Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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