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CVE-2026-89835

f2fs: avoid NULL checkpoint thread access in sysfs

Published
Last modified
published
Not listed in CISA KEV
Fix
Fixed in 6.6.160, 6.12.110, 6.18.51, 7.2.5
None on Exploit-DB, Metasploit or GitHub

Summary

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.

Timeline

  1. CVE published
  2. Record last updated

Affected versions

  • Linux Linux

    Version range not reported

  • Linux Linux

    5.12

  • KernelLinux

    From 5.12.0 · fixed in 6.6.160; From 6.7.0 · fixed in 6.12.110; From 6.13.0 · fixed in 6.18.51; From 6.19.0 · fixed in 7.2.5

References 6

git.kernel.org