{"id":"CVE-2026-89750","summary":"tracing/user_events: Clear copied tracing state before fork duplication","details":"In the Linux kernel, the following vulnerability has been resolved:\n\ntracing/user_events: Clear copied tracing state before fork duplication\n\ndup_task_struct() copies user_event_mm from the parent into the child,\nwithout grabbing a reference to it. user_event_mm_dup() should\nreplace it, but it leaves that copied pointer unmodified if\nuser_event_mm_alloc() fails.\n\nWhen the child exits, user_event_mm_remove() decrements a reference\nthe child never owned, which ultimately frees user_event_mm, while\nthe parent still as a stale pointer to it. This creates a UAF, which\nKASAN reports as:\n\n    BUG: KASAN: slab-use-after-free in\n    current_user_event_mm+0x51/0x1d0 Write of size 4 at addr\n    ffff888005010d30 by task init/44\n\n    Call Trace:\n     \u003cTASK\u003e\n     kasan_report+0xce/0x100\n     kasan_check_range+0x10f/0x1e0\n     current_user_event_mm+0x51/0x1d0\n     user_events_ioctl+0x82e/0x15c0\n     __x64_sys_ioctl+0x139/0x1c0\n     do_syscall_64+0xce/0x450\n     entry_SYSCALL_64_after_hwframe+0x77/0x7f\n\n    Allocated by task 44:\n     __kasan_kmalloc+0x8f/0xa0\n     __kmalloc_cache_noprof+0x180/0x3a0\n     user_event_mm_alloc+0x3c/0x1f0\n     current_user_event_mm+0x88/0x1d0\n\n    Freed by task 42:\n     __kasan_slab_free+0x43/0x70\n     kfree+0x13a/0x390\n     process_one_work+0x696/0xf90\n     worker_thread+0x420/0xba0\n\nThe fix simply clears the copied pointer before any possible failure.\nIn case of failure, the child then has nothing to free.","modified":"2026-09-14T03:46:36.188762508Z","published":"2026-09-11T19:46:54.565Z","database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/89xxx/CVE-2026-89750.json","cna_assigner":"Linux"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/25a0758cf6bdbfddac2be71124c9bd0692f4b0b1"},{"type":"WEB","url":"https://git.kernel.org/stable/c/390f6bd8583d177029d9df4bea6667509e55a765"},{"type":"WEB","url":"https://git.kernel.org/stable/c/63b39e49a4c9d68e010e96b26fc7374f0864f2b1"},{"type":"WEB","url":"https://git.kernel.org/stable/c/b799f67119aff179719a0b1e12441ebbdaaf62f9"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/89xxx/CVE-2026-89750.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-89750"},{"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":"7235759084a4f8524a46bd2638885ff3b34ce279"},{"fixed":"63b39e49a4c9d68e010e96b26fc7374f0864f2b1"},{"fixed":"25a0758cf6bdbfddac2be71124c9bd0692f4b0b1"},{"fixed":"b799f67119aff179719a0b1e12441ebbdaaf62f9"},{"fixed":"390f6bd8583d177029d9df4bea6667509e55a765"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-89750.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"6.4.0"},{"fixed":"6.12.109"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"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-2026-89750.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"}]}