CVE-2026-80775

CVE CVE-2026-80775EUVD EUVD-2026-71418Veröffentlicht 2026-09-04T15:12:47.000Z

Was das Advisory beschreibt

In the Linux kernel, the following vulnerability has been resolved: futex: Fix race on the initial mm->futex.phash.ref allocation futex_hash_allocate() allocates mm->futex.phash.ref without any locking. Commit d9b05321e21e ("futex: Move futex_hash_free() back to __mmput()") moved the allocation here and assumed that the process has just a single thread at this point. Commit ee9dce44362b ("futex: Drop CLONE_THREAD requirement for private default hash alloc") widened need_futex_hash_allocate_default() to cover any CLONE_VM clone, but left out vfork because the parent is suspended and cannot race. That no longer holds once vfork is nested. If a vfork child calls vfork again and is then killed with SIGKILL, the parent is released from its vfork wait and runs concurrently with the grandchild in the same mm. Neither of them went through futex_hash_allocate_default(). When both call prctl(PR_FUTEX_HASH, PR_FUTEX_HASH_SET_SLOTS) at the same time, each one sees mm->futex.phash.ref as NULL and stores its own percpu counter. Only the last store survives. The counter stored first is no longer reachable from the mm, so the references on it are not seen by __futex_ref_atomic_end(). A private hash that still has references is then considered dead and freed, and a task that still holds one of its buckets writes into freed memory in futex_q_lock(). Store the counter once with cmpxchg() and let the loser free_percpu() its own. The initial reference has to be taken before the store, otherwise another task can install a private hash while the counter is still 0.

Quelle: EUVD (ENISA), im Wortlaut der Meldung.

Produkte, die das Advisory nennt

Diese Angaben stammen aus der Meldung selbst, nicht aus einer Prüfung durch uns.

• Linux — Linux d9b05321e21e4b218de4ce8a590bf375f58b6346 <86d12b34bafc9a4c271a9edefea88855a934d6e5; d9b05321e21e4b218de4ce8a590bf375f58b6346 <bde0238083647381d4747355c5a19115a3422b96; 6.17; patch: 7.1.11; patch: 0; patch: 7.3-rc1; patch: 6.18.47; d9b05321e21e4b218de4ce8a590bf375f58b6346 <c4b4972d8edcdf50b6518f55119e129d2f668a10; d9b05321e21e4b218de4ce8a590bf375f58b6346 <ff252ed45c8263525f2f54d81c5fa6d547fba344; patch: 7.2.1

Die genannten Versionen sind die Angabe der Meldung. Patchlage vergleicht keine Versionsnummern und leitet aus ihnen keine Aussage ab — welche Version installiert ist, muss ein Mensch nachsehen.

Im Produktkatalog geführt

Für diese Produkte kann ein Bestand in Patchlage erfasst werden. Ein Advisory dazu erscheint am Morgen danach im Lagebericht.

• Linux — Linux

Patchlage meldet Treffer und Verdachtsfälle. Zu allem anderen sagt dieses System nichts — weder diese Seite noch der Lagebericht behauptet je, dass ein Bestand sicher ist.