{"id":"CVE-2026-89835","summary":"f2fs: avoid NULL checkpoint thread access in sysfs","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nf2fs: avoid NULL checkpoint thread access in sysfs\n\ncheckpoint_merge can be enabled even when no checkpoint merge thread is\nrunning. A read-only mount is one case: f2fs does not start\nf2fs_issue_ckpt there, but ckpt_thread_ioprio is still writable through\nsysfs.\n\nThe ckpt_thread_ioprio store path updates the saved ioprio value and,\nwhen checkpoint_merge is enabled, calls set_task_ioprio() for the\ncheckpoint thread. If cprc-\u003ef2fs_issue_ckpt is NULL, that dereferences a\nNULL task pointer.\n\nProtect ckpt_thread_ioprio sysfs writes with s_umount as well, so the\ncheckpoint thread cannot disappear under the store path while updating\nits ioprio.","modified":"2026-09-18T03:48:33.143294172Z","published":"2026-09-16T10:31:08.636Z","database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/89xxx/CVE-2026-89835.json","cna_assigner":"Linux"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/5cb33b00c8fbb6e8f1fa3d281c3036d5f7c7c41f"},{"type":"WEB","url":"https://git.kernel.org/stable/c/8f3b99c50dd0da1777994ce7c7e60d39b9f60f4b"},{"type":"WEB","url":"https://git.kernel.org/stable/c/a6573f3ffc19542de9ebc1a2b1f930fd48ba538c"},{"type":"WEB","url":"https://git.kernel.org/stable/c/aefcec3bebdeed2bff444378122300763325ba23"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/89xxx/CVE-2026-89835.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-89835"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"e65920661708b7c0f3db45c9cd5d0095034ee37f"},{"fixed":"a6573f3ffc19542de9ebc1a2b1f930fd48ba538c"},{"fixed":"aefcec3bebdeed2bff444378122300763325ba23"},{"fixed":"8f3b99c50dd0da1777994ce7c7e60d39b9f60f4b"},{"fixed":"5cb33b00c8fbb6e8f1fa3d281c3036d5f7c7c41f"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-89835.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"5.12.0"},{"fixed":"6.12.110"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.18.51"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"7.2.5"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-89835.json"}}],"schema_version":"1.9.0"}