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However, this introduced a use-after-free because\nupdate_super_work calls ext4_notify_error_sysfs() -> sysfs_notify() which\naccesses the kobject's kernfs_node after it has been freed by kobject_del()\nin ext4_unregister_sysfs():\n\n update_super_work ext4_put_super\n ----------------- --------------\n ext4_unregister_sysfs(sb)\n kobject_del(&sbi->s_kobj)\n __kobject_del()\n sysfs_remove_dir()\n kobj->sd = NULL\n sysfs_put(sd)\n kernfs_put() // RCU free\n ext4_notify_error_sysfs(sbi)\n sysfs_notify(&sbi->s_kobj)\n kn = kobj->sd // stale pointer\n kernfs_get(kn) // UAF on freed kernfs_node\n ext4_journal_destroy()\n flush_work(&sbi->s_sb_upd_work)\n\nInstead of reordering the teardown sequence, fix this by making\next4_notify_error_sysfs() detect that sysfs has already been torn down\nby checking s_kobj.state_in_sysfs, and skipping the sysfs_notify() call\nin that case. A dedicated mutex (s_error_notify_mutex) serializes\next4_notify_error_sysfs() against kobject_del() in ext4_unregister_sysfs()\nto prevent TOCTOU races where the kobject could be deleted between the\nstate_in_sysfs check and the sysfs_notify() call."}], "metrics": [{"cvssV3_1": {"version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H", "baseScore": 7.8, "baseSeverity": "HIGH"}}], "affected": [{"product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["fs/ext4/ext4.h", "fs/ext4/super.c", "fs/ext4/sysfs.c"], "versions": [{"version": "52c3a04f9ec2a16a4204d6274db338cb8d5b2d74", "lessThan": "c8fe17a1b308c3d8c703ebfb049b325f844342c3", "status": "affected", "versionType": "git"}, {"version": "b98535d091795a79336f520b0708457aacf55c67", "lessThan": "c4d829737329f2290dd41e290b7d75effdb2a7ff", "status": "affected", "versionType": "git"}, {"version": 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However, this introduced a use-after-free because\nupdate_super_work calls ext4_notify_error_sysfs() -> sysfs_notify() which\naccesses the kobject's kernfs_node after it has been freed by kobject_del()\nin ext4_unregister_sysfs():\n\n update_super_work ext4_put_super\n ----------------- --------------\n ext4_unregister_sysfs(sb)\n kobject_del(&sbi->s_kobj)\n __kobject_del()\n sysfs_remove_dir()\n kobj->sd = NULL\n sysfs_put(sd)\n kernfs_put() // RCU free\n ext4_notify_error_sysfs(sbi)\n sysfs_notify(&sbi->s_kobj)\n kn = kobj->sd // stale pointer\n kernfs_get(kn) // UAF on freed kernfs_node\n ext4_journal_destroy()\n flush_work(&sbi->s_sb_upd_work)\n\nInstead of reordering the teardown sequence, fix this by making\next4_notify_error_sysfs() detect that sysfs has already been torn down\nby checking s_kobj.state_in_sysfs, and skipping the sysfs_notify() call\nin that case. A dedicated mutex (s_error_notify_mutex) serializes\next4_notify_error_sysfs() against kobject_del() in ext4_unregister_sysfs()\nto prevent TOCTOU races where the kobject could be deleted between the\nstate_in_sysfs check and the sysfs_notify() call."}], "id": "CVE-2026-31446", "lastModified": "2026-05-07T19:21:44.833", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "LOCAL", "availabilityImpact": "HIGH", "baseScore": 7.8, "baseSeverity": "HIGH", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "REQUIRED", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H", "version": "3.1"}, "exploitabilityScore": 1.8, "impactScore": 5.9, "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "type": "Secondary"}]}, "published": "2026-04-22T14:16:38.340", "references": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/034053378dd81837fd6c7a43b37ee2e58d4f0b4e"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/08b10e6f37fc533a759e9833af0692242e8b3f93"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/9449f99ba04f5dd1c8423ad8a90b3651d7240d1d"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/c4d829737329f2290dd41e290b7d75effdb2a7ff"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/c8fe17a1b308c3d8c703ebfb049b325f844342c3"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/c97e282f7bfd0c3554c63d289964a5ca6a1d2ffe"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/d15e4b0a418537aafa56b2cb80d44add83e83697"}], "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "vulnStatus": "Analyzed", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-416"}], "source": "nvd@nist.gov", "type": "Primary"}]}

{"bugzilla": {"description": "kernel: ext4: fix use-after-free in update_super_work when racing with umount", "id": "2460704", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2460704"}, "csaw": false, "cvss3": {"cvss3_base_score": "7.0", "cvss3_scoring_vector": "CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H", "status": "draft"}, "cwe": "CWE-825", "details": ["A flaw was found in the Linux kernel's ext4 filesystem. This vulnerability, a use-after-free, occurs due to a timing issue when the `update_super_work` function attempts to access memory that has already been released during a filesystem unmount operation. A local attacker could potentially exploit this flaw, leading to system instability or a denial of service (DoS)."], "name": "CVE-2026-31446", "package_state": [{"cpe": "cpe:/o:redhat:enterprise_linux:10", "fix_state": "Affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 10"}, {"cpe": "cpe:/o:redhat:enterprise_linux:6", "fix_state": "Out of support scope", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 6"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Not affected", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Not affected", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 9"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Affected", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 9"}], "public_date": "2026-04-22T00:00:00Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2026-31446\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-31446\nhttps://lore.kernel.org/linux-cve-announce/2026042246-CVE-2026-31446-8993@gregkh/T"], "threat_severity": "Moderate"}

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