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.
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.
Metrics
Affected Vendors & Products
Advisories
No advisories yet.
Fixes
Solution
No solution given by the vendor.
Workaround
No workaround given by the vendor.
References
History
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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MITRE
Status: PUBLISHED
Assigner: Linux
Published:
Updated: 2026-09-16T10:31:08.636Z
Reserved: 2026-09-11T19:38:34.769Z
Link: CVE-2026-89835
Vulnrichment
No data.
NVD
Status : Received
Published: 2026-09-16T11:16:50.290
Modified: 2026-09-16T11:16:50.290
Link: CVE-2026-89835
Redhat
No data.
OpenCVE Enrichment
No data.
Weaknesses
No weakness.