---
cve: "CVE-2026-74572"
severity: "HIGH"
cvss: 7.5
epss: "35%"
vendor: "Linux"
kev: false
exploited: false
published: "2026-08-15 13:18:02"
tags: [cve, security, high]
source: tsecurity.de CVE-Dossier
exported: "2026-09-02T21:11:21+02:00"
---

# CVE-2026-74572

> 7.5 HIGH

## Beschreibung

In the Linux kernel, the following vulnerability has been resolved:

btrfs: zoned: fix deadlock between metadata writeback and transaction commit

When writing out metadata extent buffers in a zoned filesystem,
btree_writepages() holds fs_info->zoned_meta_io_lock across the whole
writeback loop, including the call to btrfs_check_meta_write_pointer() ->
check_bg_is_active().

For the tree-log block group, check_bg_is_active() may fail to activate
the zone and fall back to btrfs_zone_finish_one_bg() to free an active
zone. That path waits for the running transaction to commit while still
holding zoned_meta_io_lock, but the committer needs that same lock to
write out the tree extents, so the two tasks deadlock:

  Task A (kworker, metadata writeback)      Task B (fsstress, transaction commit)
  ------------------------------------      -------------------------------------
  wb_workfn()                               btrfs_commit_transaction(T)
   btree_writepages()                        btrfs_write_and_wait_transaction()
    btrfs_zoned_meta_io_lock()                btrfs_write_marked_extents()
    btrfs_check_meta_write_pointer()           btree_writepages()
     check_bg_is_active() [treelog_bg]          btrfs_zoned_meta_io_lock()
      btrfs_zone_finish_one_bg()               
        do_zone_finish()
         btrfs_inc_block_group_ro()
          btrfs_wait_for_commit()
           

The sibling branch in check_bg_is_active() already drops zoned_meta_io_lock
around do_zone_finish() for this exact reason. Do the same in the tree-log
branch: release the lock around btrfs_zone_finish_one_bg() and re-acquire
it afterwards. The lock only protects fs_info->active_{meta,system}_bg,
which this branch does not touch, and ctx->zoned_bg keeps a reference to
the block group across the unlock, so nothing is lost while the lock
is dropped.

This hang occasionally reproduces with fstests generic/475 on a zoned
btrfs filesystem.

## CVSS-Vektor

```
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
```

| Metrik | Wert | Bewertung |
|---|---|---|
| AV Angriffsvektor | Netzwerk | bad |
| AC Komplexität | Gering | bad |
| PR Privilegien | Keine | bad |
| UI Interaktion | Keine | bad |
| S Scope | Unverändert | good |
| C Vertraulichkeit | Keine | good |
| I Integrität | Keine | good |
| A Verfügbarkeit | Hoch | bad |

## Patch verfügbar (OSV)

- Kernel ≥ 6.6.151
- Kernel ≥ 6.12.103
- Kernel ≥ 6.18.44
- Kernel ≥ 7.1.8

## Referenzen

- <https://git.kernel.org/stable/c/18577e77c2c8adaadf1f7c6e9bcd1c0b14e5dcdd>
- <https://git.kernel.org/stable/c/c3320873e0c04ce7b746fc8fe948f07bbbbdec33>
- <https://git.kernel.org/stable/c/deddd28fd83c264ee2ff5cd6b34449a9f1be6112>
- <https://git.kernel.org/stable/c/75859a7cd77cd2ddaddbcb963e3fcd34738953af>
- <https://git.kernel.org/stable/c/1ebe51c29fa9755d5b2fea28727c051117907cf8>

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/cve?cve=CVE-2026-74572) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI BITS_