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

f2fs: avoid NULL checkpoint thread access in sysfs

checkpoint_merge can be enabled even when no checkpoint merge thread is
running. A read-only mount is one case: f2fs does not start
f2fs_issue_ckpt there, but ckpt_thread_ioprio is still writable through
sysfs.

The ckpt_thread_ioprio store path updates the saved ioprio value and,
when checkpoint_merge is enabled, calls set_task_ioprio() for the
checkpoint thread. If cprc->f2fs_issue_ckpt is NULL, that dereferences a
NULL task pointer.

Protect ckpt_thread_ioprio sysfs writes with s_umount as well, so the
checkpoint thread cannot disappear under the store path while updating
its ioprio.
Advisories
Source ID Title
Debian DLA Debian DLA DLA-4817-1 linux-6.12 security update
Debian DSA Debian DSA DSA-6528-1 linux security update
Fixes

Solution

No solution given by the vendor.


Workaround

No workaround given by the vendor.

History

Fri, 30 Oct 2026 12:45:00 +0000


Wed, 21 Oct 2026 13:15:00 +0000


Fri, 18 Sep 2026 10:00:00 +0000

Type Values Removed Values Added
Weaknesses CWE-476

Wed, 16 Sep 2026 10:45:00 +0000

Type Values Removed Values Added
Description In the Linux kernel, the following vulnerability has been resolved: f2fs: avoid NULL checkpoint thread access in sysfs checkpoint_merge can be enabled even when no checkpoint merge thread is running. A read-only mount is one case: f2fs does not start f2fs_issue_ckpt there, but ckpt_thread_ioprio is still writable through sysfs. The ckpt_thread_ioprio store path updates the saved ioprio value and, when checkpoint_merge is enabled, calls set_task_ioprio() for the checkpoint thread. If cprc->f2fs_issue_ckpt is NULL, that dereferences a NULL task pointer. Protect ckpt_thread_ioprio sysfs writes with s_umount as well, so the checkpoint thread cannot disappear under the store path while updating its ioprio.
Title f2fs: avoid NULL checkpoint thread access in sysfs
First Time appeared Linux
Linux linux Kernel
CPEs cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
Vendors & Products Linux
Linux linux Kernel
References

Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: Linux

Published:

Updated: 2026-10-30T12:33:14.173Z

Reserved: 2026-09-11T19:38:34.769Z

Link: CVE-2026-89835

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-09-16T11:16:50.290

Modified: 2026-10-30T13:20:30.740

Link: CVE-2026-89835

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-09-18T09:45:06Z

Weaknesses