{"id":"CVE-2026-89600","summary":"fanotify: fix use-after-free of file range info","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nfanotify: fix use-after-free of file range info\n\nfsnotify_pre_content() builds its file_range on the triggering task's\nstack. fanotify_alloc_perm_event() saves a pointer to range.pos in the\nheap-allocated permission event so copy_range_info_to_user() can report\nthe offset later.\n\nThe event reader can set the event state to FAN_EVENT_REPORTED and then\nsleep while preparing the file descriptor. If a signal interrupts the\ntriggering task at that point, fanotify_get_response() changes the state\nto FAN_EVENT_CANCELED and returns. This unwinds the file_range stack\nframe while the reader still owns the event. The reader then dereferences\npevent-\u003eppos and copies the stale stack value to userspace.\n\nKASAN reported:\n\n  BUG: KASAN: use-after-free in fanotify_read+0x293e/0x2970\n  Read of size 8 at addr ffff88811434fc50 by task fanotify_inotif/95\n  Call Trace:\n   fanotify_read+0x293e/0x2970\n   vfs_read+0x177/0xa20\n   ksys_read+0xf7/0x1c0\n   do_syscall_64+0xf9/0x540\n   entry_SYSCALL_64_after_hwframe+0x77/0x7f\n\nStore the range position directly in the permission event and use\nFANOTIFY_NO_RANGE when range information is unavailable. The event remains\nalive until the reader finishes, so the reported offset no longer depends\non the triggering task's stack.","modified":"2026-09-13T03:47:19.593222165Z","published":"2026-09-11T19:45:03.450Z","database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/89xxx/CVE-2026-89600.json"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/66aa9a9e6481bfa512ee5b6380eaaec455a954d2"},{"type":"WEB","url":"https://git.kernel.org/stable/c/b8f73b163b646bc56d4dce9c697a578e333f4894"},{"type":"WEB","url":"https://git.kernel.org/stable/c/d7f1cf5be33ef0175a4e8ed8687aeb98fb00a851"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/89xxx/CVE-2026-89600.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-89600"},{"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":"870499bc1d4dc04cba1f63dd5e7bc02b983e2458"},{"fixed":"66aa9a9e6481bfa512ee5b6380eaaec455a954d2"},{"fixed":"b8f73b163b646bc56d4dce9c697a578e333f4894"},{"fixed":"d7f1cf5be33ef0175a4e8ed8687aeb98fb00a851"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-89600.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"6.14.0"},{"fixed":"6.18.50"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"7.2.4"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-89600.json"}}],"schema_version":"1.9.0"}