GHSA-2HJF-MQWW-7576
Vulnerability from github – Published: 2026-09-16 12:30 – Updated: 2026-10-30 15:33In 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": [],
"aliases": [
"CVE-2026-89835"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-09-16T11:16:50Z",
"severity": null
},
"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.",
"id": "GHSA-2hjf-mqww-7576",
"modified": "2026-10-30T15:33:28Z",
"published": "2026-09-16T12:30:38Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-89835"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/22760e3e9cecbddc475edc91600787abf407a302"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/54196bcfde998fb37009f50e0ef16498f651f0f9"
},
{
"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"
}
],
"schema_version": "1.4.0",
"severity": []
}
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