CVE-2026-89835: vulnerability in Linux
f2fs: avoid NULL checkpoint thread access in sysfs
Published
3Vexday Risk Score
No sign of exploitation. No public exploitation artifact known so far.
ssvc Trackepss 0.2%
exploitation probability
0.2%top 90% of all CVEs
observed exploitation
nono source reports it
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.
Affected products
Linux · LinuxRelated CVEs — Linux
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