xfs: deadlock when xfs_sync_sb_buf holds buffer locks across sync commit
Key facts
- Attack vector
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- Privileges required
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- User interaction
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- Attack complexity
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- Impact type
- —
- Confidentiality · integrity · availability
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- Fix status
- Partial Red Hat: 6 without a fix
No CVSS vector from any source. Fix status from CNA and Red Hat.
Summary
In the Linux kernel's XFS filesystem, xfs_sync_sb_buf() holds the superblock and realtime superblock buffer locks across a synchronous xfs_trans_commit(), which flushes the CIL push workqueue. If a shutdown occurs during the CIL push, xfs_buf_item_unpin() must lock the same buffers to fail them, and the two paths deadlock. Kernels from 4.18 are affected, and Red Hat rates it Moderate with no available fix for RHEL 7 through 10 or OpenShift Container Platform 4 and 5.
Written with Claude Haiku 5.5 from the sources below · 2026-10-30
Description from the CNA
In the Linux kernel, the following vulnerability has been resolved: xfs: don't hold buffer locks across sync transaction commit in xfs_sync_sb_buf xfs_sync_sb_buf() holds sb/rtsb buffer locks across a synchronous xfs_trans_commit(), which flushes the CIL push workqueue internally. If shutdown occurs during the CIL push, xfs_buf_item_unpin() needs to lock these buffers to fail them, causing a deadlock: setlabel: holds buf lock -> flush_workqueue(xfs-cil) CIL push worker: xfs_buf_item_unpin -> xfs_buf_lock(same buf) Remove the xfs_trans_bhold() calls so that commit releases the buffer locks normally. After the sync commit, re-acquire the buffers via mp->m_sb_bp / mp->m_rtsb_bp for the on-disk writeback.
Why it matters now
SSVC decision points
Not available: CISA has not published SSVC decision points for this record.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| Linux | Linux | 4.18 and later | 5.10.273, 5.15.224, 6.1.191, 6.6.161, 6.12.115, 6.18.59, 7.2.13, 7.3 | Patch available | CNA |
- Linux VendorLinux Affected 4.18 and later Fixed in 5.10.273, 5.15.224, 6.1.191, 6.6.161, 6.12.115, 6.18.59, 7.2.13, 7.3 Patch available CNA
Remediation
Update to a fixed stable kernel: 5.10.273, 5.15.224, 6.1.191, 6.6.161, 6.12.115, 6.18.59, 7.2.13, or 7.3. The fix removes the xfs_trans_bhold() calls so the commit releases the buffer locks, and xfs_sync_sb_buf() re-acquires the buffers through mp->m_sb_bp and mp->m_rtsb_bp for the on-disk writeback.
Written with Claude Haiku 5.5 from the sources below · 2026-10-30
- Fix · CNA Linux (Linux) Fixed in 5.10.273, 5.15.224, 6.1.191, 6.6.161, 6.12.115, 6.18.59, 7.2.13, 7.3
Vendor assessments
Red Hat
Red Hat rating: Moderate. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| Red Hat Enterprise Linux 10 | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux 7 | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux 8 | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux 9 | Affected | No fix yet: Fix deferred |
| Red Hat OpenShift Container Platform 4 | Affected | No fix yet: Fix deferred |
| Red Hat OpenShift Container Platform 5 | Affected | No fix yet: Fix deferred |
Not affected: 1 product
- Red Hat Enterprise Linux 6
Timeline
- 2026-10-28 Threatist record created from CVE-2026-99132
- 2026-10-28 Alias added: GHSA-vc85-4r75-3q3q
- 2026-10-29 Affected versions changed · Red Hat
- 2026-10-29 CVSS score added · Red Hat
- 2026-10-30 Affected versions changed · Red Hat
- 2026-10-30 Fix available: Linux/Linux@16468281da17263095bd1906cf2d16a972f10791, Linux/Linux@45f124f3902bfae6a366d124db04f707264176fb, Linux/[email protected] +7 · CNA
- 2026-10-30 5 new references · CNA
References
Other 8
- https://git.kernel.org/stable/c/16468281da17263095bd1906cf2d16a972f10791
- https://git.kernel.org/stable/c/45f124f3902bfae6a366d124db04f707264176fb
- https://git.kernel.org/stable/c/d900946853c2d183fa0e199bae9ddbcd21795a18
- https://git.kernel.org/stable/c/83b2e511cf9ba22904b167e00fcbd85169b50b2c
- https://git.kernel.org/stable/c/acd7f2f9b822b6e126f3e3c99c173e62aa315b6f
- https://git.kernel.org/stable/c/e5456dec79c71c8ef8f9f9adb77d320f113b34db
- https://git.kernel.org/stable/c/6353e5cd8c43d6e805cacbfbfecf4103571a7ff8
- https://git.kernel.org/stable/c/41a28c865d1d5843f8cb9e0af17a8f4d9e2961ff
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Sources
- CVE-2026-99132 · CVE Program
- CVE-2026-99132 · NVD
- FIRST EPSS
- GHSA-vc85-4r75-3q3q · GitHub Advisory Database · CC BY 4.0
- CVE-2026-99132 · Red Hat security data · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences