CVE-2026-90003

Description

In the Linux kernel, the following vulnerability has been resolved: futex: Prevent rcuwait use-after-free during requeue PI On PREEMPT_RT, FUTEX_CMP_REQUEUE_PI can trigger a KASAN report (slab-out-of-bounds) in futex_requeue_pi_complete() invocation of rcuwait_wake_up(). The futex_q used by futex_wait_requeue_pi() is allocated on the waiter's stack. An early wakeup can race with a PI requeue as follows: waiter requeue task ------ ------------ futex_wait_requeue_pi() futex_do_wait() schedule() futex_requeue futex_proxy_trylock_atomic() futex_requeue_pi_prepare() Q_REQUEUE_PI_NONE -> Q_REQUEUE_PI_IN_PROGRESS * timeout/ signal wakes waiter * futex_requeue_pi_wakeup_sync() Q_REQUEUE_PI_IN_PROGRESS -> Q_REQUEUE_PI_WAIT requeue_pi_wake_futex futex_requeue_pi_complete() cmpxchg Q_REQUEUE_PI_WAIT -> Q_REQUEUE_PI_LOCKED rcuwait_wait_event() if (atomic_read(&q->requeue_state) != Q_REQUEUE_PI_WAIT) break /* no schedule() */ /* q.pi_state->owner == current */ futex_private_hash_put() /* return from syscall */ rcuwait_wake_up(&q->requeue_wait) /* q is gone */ futex_requeue_pi_complete() publishes Q_REQUEUE_PI_LOCKED before calling rcuwait_wake_up(). The waiter observes this state in rcuwait_wait_event() before invoking schedule() in rcuwait_wait_event(). Here, the waiter is free leave the syscall before requeue task can complete the wake. To address this race skip rcuwait_wake_up() in the Q_REQUEUE_PI_LOCKED case. This state is only published by requeue_pi_wake_futex(), which saves q->task before futex_requeue_pi_complete() and wakes the waiter via wake_up_state(). This wake is intended to wake the waiter from its futex_do_wait() sleep. If the waiter is still sleeping there, it can not get into the Q_REQUEUE_PI_WAIT state (and require this removed wake). Should the waiter be woken up from futex_do_wait() by other means (as in this example) and sleep in futex_requeue_pi_wakeup_sync() then the wake_up_state() from requeue_pi_wake_futex() will wake it, too. Should the waiter task terminate before wake_up_state() had a chance to wake the task then the task pointer does not become invalid because the futex_hash_bucket::lock is held and the task pointer is RCU protected. [bigeasy: Updated comment and commit message]

Gravité et risque d'exploitation

CVE-2026-90003 obtient un score CVSS de 7.8/10, soit une gravité élevée. Selon le modèle EPSS, la probabilité qu'elle soit exploitée dans les 30 prochains jours est de 0.16 %, ce qui la place devant 5.3 % des CVE référencées.

Que faire ?

• Vérifiez si Linux (versions <=6.1.*, <=6.12.*, <e4a4ccfa470f910b747b3ee8d18670ed8ac8a236, 0, <7d1559126d86be6e4f6a85663dfbfe85caa47e37, 6.1.188, 6.18.51, <=6.6.*, 7.2.5, <5.15, 6.6.157, 07d91ef510fb16a2e0ca7453222105835b7ba3b8, <220ee9e04ca3b7f014c000264aa6c884f036c86e, <a3b8d46fe401cba3a5c46dea610e6eb3dc15370e, 5.15, <=6.18.*, 6.12.110, <=7.2.*, <81aadbd09bf1dcd3238212f336ba699503557ae8, <=*, <244f301759fd34b1dd0b4192ce44f8ef224e027d, 7.3) est présent sur votre parc.
• Appliquez le correctif ou la version corrigée indiqués dans les références de l'éditeur.
• À défaut de correctif, limitez l'exposition (filtrage réseau, désactivation du composant).
• Automatisez la détection : les agents CVE Heimdall (gratuits, open source) corrèlent l'inventaire de vos serveurs avec la base CVE.

Références

• https://git.kernel.org/stable/c/220ee9e04ca3b7f014c000264aa6c884f036c86e
• https://git.kernel.org/stable/c/81aadbd09bf1dcd3238212f336ba699503557ae8
• https://git.kernel.org/stable/c/244f301759fd34b1dd0b4192ce44f8ef224e027d
• https://git.kernel.org/stable/c/7d1559126d86be6e4f6a85663dfbfe85caa47e37
• https://git.kernel.org/stable/c/e4a4ccfa470f910b747b3ee8d18670ed8ac8a236
• https://git.kernel.org/stable/c/a3b8d46fe401cba3a5c46dea610e6eb3dc15370e