{"id":"CVE-2026-89835","state":"PUBLISHED","title":"f2fs: avoid NULL checkpoint thread access in sysfs","description":"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->f2fs_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.","publishedAt":"2026-09-16T10:31:08.636Z","updatedAt":"2026-10-30T12:33:14.173Z","severity":null,"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"e65920661708b7c0f3db45c9cd5d0095034ee37f","status":"affected","lessThan":"54196bcfde998fb37009f50e0ef16498f651f0f9","versionType":"git"},{"version":"e65920661708b7c0f3db45c9cd5d0095034ee37f","status":"affected","lessThan":"22760e3e9cecbddc475edc91600787abf407a302","versionType":"git"},{"version":"e65920661708b7c0f3db45c9cd5d0095034ee37f","status":"affected","lessThan":"a6573f3ffc19542de9ebc1a2b1f930fd48ba538c","versionType":"git"},{"version":"e65920661708b7c0f3db45c9cd5d0095034ee37f","status":"affected","lessThan":"aefcec3bebdeed2bff444378122300763325ba23","versionType":"git"},{"version":"e65920661708b7c0f3db45c9cd5d0095034ee37f","status":"affected","lessThan":"8f3b99c50dd0da1777994ce7c7e60d39b9f60f4b","versionType":"git"},{"version":"e65920661708b7c0f3db45c9cd5d0095034ee37f","status":"affected","lessThan":"5cb33b00c8fbb6e8f1fa3d281c3036d5f7c7c41f","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/f2fs/sysfs.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"5.12","status":"affected"},{"version":"0","status":"unaffected","lessThan":"5.12","versionType":"semver"},{"version":"6.1.191","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.160","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.110","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.51","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.2.5","status":"unaffected","lessThanOrEqual":"7.2.*","versionType":"semver"},{"version":"7.3","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/f2fs/sysfs.c"]}],"references":["https://git.kernel.org/stable/c/54196bcfde998fb37009f50e0ef16498f651f0f9","https://git.kernel.org/stable/c/22760e3e9cecbddc475edc91600787abf407a302","https://git.kernel.org/stable/c/a6573f3ffc19542de9ebc1a2b1f930fd48ba538c","https://git.kernel.org/stable/c/aefcec3bebdeed2bff444378122300763325ba23","https://git.kernel.org/stable/c/8f3b99c50dd0da1777994ce7c7e60d39b9f60f4b","https://git.kernel.org/stable/c/5cb33b00c8fbb6e8f1fa3d281c3036d5f7c7c41f"],"weaknesses":[],"ingestedAt":"2026-10-30T12:52:04.348Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/89xxx/CVE-2026-89835.json","commit":"1f312381e38164a43607eebab851b151dd16861e","baselineCommit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-89835","state":"PUBLISHED","datePublished":"2026-09-16T10:31:08.636Z","dateUpdated":"2026-10-30T12:33:14.173Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-09-11T19:38:34.769Z"},"containers":{"cna":{"title":"f2fs: avoid NULL checkpoint thread access in sysfs","descriptions":[{"lang":"en","value":"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->f2fs_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."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"e65920661708b7c0f3db45c9cd5d0095034ee37f","status":"affected","lessThan":"54196bcfde998fb37009f50e0ef16498f651f0f9","versionType":"git"},{"version":"e65920661708b7c0f3db45c9cd5d0095034ee37f","status":"affected","lessThan":"22760e3e9cecbddc475edc91600787abf407a302","versionType":"git"},{"version":"e65920661708b7c0f3db45c9cd5d0095034ee37f","status":"affected","lessThan":"a6573f3ffc19542de9ebc1a2b1f930fd48ba538c","versionType":"git"},{"version":"e65920661708b7c0f3db45c9cd5d0095034ee37f","status":"affected","lessThan":"aefcec3bebdeed2bff444378122300763325ba23","versionType":"git"},{"version":"e65920661708b7c0f3db45c9cd5d0095034ee37f","status":"affected","lessThan":"8f3b99c50dd0da1777994ce7c7e60d39b9f60f4b","versionType":"git"},{"version":"e65920661708b7c0f3db45c9cd5d0095034ee37f","status":"affected","lessThan":"5cb33b00c8fbb6e8f1fa3d281c3036d5f7c7c41f","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/f2fs/sysfs.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"5.12","status":"affected"},{"version":"0","status":"unaffected","lessThan":"5.12","versionType":"semver"},{"version":"6.1.191","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.160","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.110","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.51","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.2.5","status":"unaffected","lessThanOrEqual":"7.2.*","versionType":"semver"},{"version":"7.3","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/f2fs/sysfs.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/54196bcfde998fb37009f50e0ef16498f651f0f9"},{"url":"https://git.kernel.org/stable/c/22760e3e9cecbddc475edc91600787abf407a302"},{"url":"https://git.kernel.org/stable/c/a6573f3ffc19542de9ebc1a2b1f930fd48ba538c"},{"url":"https://git.kernel.org/stable/c/aefcec3bebdeed2bff444378122300763325ba23"},{"url":"https://git.kernel.org/stable/c/8f3b99c50dd0da1777994ce7c7e60d39b9f60f4b"},{"url":"https://git.kernel.org/stable/c/5cb33b00c8fbb6e8f1fa3d281c3036d5f7c7c41f"}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-10-30T12:33:14.173Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.12","versionEndExcluding":"6.1.191"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.12","versionEndExcluding":"6.6.160"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.12","versionEndExcluding":"6.12.110"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.12","versionEndExcluding":"6.18.51"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.12","versionEndExcluding":"7.2.5"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.12","versionEndExcluding":"7.3"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}