{"id":"CVE-2026-80778","summary":"futex/pi: Reject cross-mm private futex owners","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nfutex/pi: Reject cross-mm private futex owners\n\nA private futex key borrows the waiter's mm without taking an mm_users\nreference. Nevertheless, attach_to_pi_owner() currently accepts an owner\nfrom a different address space and copies the private key into the owner's\nPI state.\n\nWhen that owner exits, exit_pi_state_list() uses the saved key to find the\nhash bucket and acquires a reference to the waiter's private hash. If the\nlast user of the waiter's mm exits concurrently, futex_hash_free() frees\nthe hash while the owner still uses its bucket and reference.\n\nPrevent this by validating in attach_to_pi_owner() that, for private\nfutexes, the owner mm and waiter mm are the same. Perform the check with\nthe owner's pi_lock held and after validating owner::futex::state to\nserialize against a concurrent PI-state exit cleanup.\n\n[ tglx: Amended comment ]","modified":"2026-09-06T03:46:15.442078857Z","published":"2026-09-04T15:12:50.117Z","database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/80xxx/CVE-2026-80778.json"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/2b92e5562653b5293529f63b0300837d9dcedbd7"},{"type":"WEB","url":"https://git.kernel.org/stable/c/43b148d796aa338858792d0167cebdc12b8cb4b9"},{"type":"WEB","url":"https://git.kernel.org/stable/c/59b3732f95dda1fbd2234514d35f4fb6b5bb6d85"},{"type":"WEB","url":"https://git.kernel.org/stable/c/f7fb3e07752688842cbe0b85cf0d98c2fbf76b68"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/80xxx/CVE-2026-80778.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-80778"},{"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":"80367ad01d93ac781b0e1df246edaf006928002f"},{"fixed":"2b92e5562653b5293529f63b0300837d9dcedbd7"},{"fixed":"f7fb3e07752688842cbe0b85cf0d98c2fbf76b68"},{"fixed":"43b148d796aa338858792d0167cebdc12b8cb4b9"},{"fixed":"59b3732f95dda1fbd2234514d35f4fb6b5bb6d85"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-80778.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"6.16.0"},{"fixed":"6.18.47"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"7.1.11"}]},{"type":"ECOSYSTEM","events":[{"introduced":"7.2.0"},{"fixed":"7.2.1"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-80778.json"}}],"schema_version":"1.9.0"}