{"id":"CVE-2026-98385","summary":"sched/cache: Decouple sched_cache_group from mm to fix UAF","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nsched/cache: Decouple sched_cache_group from mm to fix UAF\n\nCurrently the sched cache grouping is by mm and the scheduling statistics\nsched_cache_stat lives in the mm structure.  This ties the life cycle\nof scheduling stats with mm.\n\nIn account_mm_sched(), the scheduling stats are accessed by\ntask-\u003emm-\u003esc_stat.  However, a task may be switching mm on one CPU when\nanother CPU is running account_mm_sched(), and possibly accessing the\nold mm that was freed.  This problem was found when running tests with\nKASAN by Hyunwoo:\n\n  https://lore.kernel.org/lkml/apPb-Dr4nPYuHQOK@v4bel/\n\nInstead of serializing the mm access by introducing extra acquisition of\nrq lock in the mm free path, extract sched_cache_stat from mm_struct,\nrename it as sched_cache_group and manage its life cycle apart from\nmm_struct with its own ref counting.  This allows us in the next patch\naccess sched_cache_group directly from task, and add a refcount\non sched_cache_group when a task links to it. This prevents the use\nafter free issue when accessing stale and released old mm and its\nsched cache stat a task switches to a new mm while account_mm_sched()\nis done elsewhere.\n\nThe other benefit of this restructure is in the future, the grouping of\ntasks to a LLC would have the flexibility to be associated with a user\ndefined grouping, or cgroup, cookie group, numa_group or others instead\nof just with a single mm address space.\n\nRename sched_cache_stat to sched_cache_group and turn it into a refcounted\nobject allocated from mm_struct.  The mm_struct now holds a pointer\n(sched_cache_grp) to this object instead of embedding it.","modified":"2026-10-13T02:47:05.947137453Z","published":"2026-10-12T05:48:52.248Z","database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/98xxx/CVE-2026-98385.json","cna_assigner":"Linux"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/28f9c0e0a0b94c5d3e1b634db545f6e1f94858c5"},{"type":"WEB","url":"https://git.kernel.org/stable/c/852ecb6bc0bc0106f44f74ba3944524732486025"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/98xxx/CVE-2026-98385.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-98385"},{"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":"df0d98475954d655571979aa061ecb07d7e00392"},{"fixed":"852ecb6bc0bc0106f44f74ba3944524732486025"},{"fixed":"28f9c0e0a0b94c5d3e1b634db545f6e1f94858c5"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-98385.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"7.2.0"},{"fixed":"7.2.9"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-98385.json"}}],"schema_version":"1.9.0"}