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CVE-2026-89732

Vulnérabilité non évaluée dans Linux (Linux)

CVSS 0.0 · Non évaluée
EPSS 0.2%
Linux•Linux•Versions : <=6.1.*, <=6.12.*, 5.15.221, <34e88f53614640b59039a46717fb6142e9871022, ddf8abd2599491cbad959c700b90ba72a5dce8d0, 5.10.270, 0, <eac233e63f9db82ba874e3cccafaafab162999e0, 7.2.4, 6.1.188, <fbe3db4b650c284df8eb4cb68eebcf270cf861b5, <=5.10.*, <=6.6.*, 6.6.157, <fd20cc68bbdb5620696ac108e8f2efd180fe2c1a, <=6.18.*, <2.6.35, <=7.2.*, <=*, <b0a6bfac0c3c3edf5b2ecaee87a09234601fe78d, <=5.15.*, <bafddd0f20b5228760be303aa69c58502e92309c, <569dd7e5dcffe1e1c6b26ca2cd3be57eb433e082, 6.18.50, <30430509c156e1df2bdafd5f1cadb160e53db5d6, 6.12.109, 2.6.35, 7.3

Description

In the Linux kernel, the following vulnerability has been resolved: usb: gadget: f_fs: Prevent deadlock during ep0 read loop Currently, ffs_ep0_read() holds ffs->mutex when it prepares to go to sleep waiting for an event. When no setup events are pending, it calls wait_event_interruptible_exclusive_locked_irq() with the mutex still held. The wait macro deliberately drops the waitqueue spinlock before sleeping but does not drop the mutex. If a userspace daemon is polling ep0 via read() and the gadget is asynchronously torn down via configfs (e.g., echo "" > UDC), a deadlock can occur: 1. The configfs teardown calls functionfs_unbind(), which queues a FUNCTIONFS_UNBIND event. 2. The daemon wakes up, consumes the event, and drops the mutex. 3. However, if the daemon loops and immediately issues another read() before exiting, it reacquires ffs->mutex and again goes into an interruptible sleep. 4. Meanwhile, functionfs_unbind() continues execution and attempts to acquire ffs->mutex to tear down ep0req. 5. The kernel deadlocks because the configfs thread is stuck in an uninterruptible sleep waiting for the mutex, while the userspace daemon is in an interruptible sleep holding the mutex forever because no more events will arrive. To fix this, we drop both the waitqueue spinlock and ffs->mutex before going to sleep, and use wait_event_interruptible_exclusive() instead. Upon waking up, we jump back to the `retry` label to safely reacquire the mutex and re-evaluate the state machine. By not sleeping with ffs->mutex held, we natively decouple gadget teardowns (which require the mutex) from userspace polling.

Gravité et risque d'exploitation

CVE-2026-89732 obtient un score CVSS de 0.0/10, soit une gravité non évaluée. Selon le modèle EPSS, la probabilité qu'elle soit exploitée dans les 30 prochains jours est de 0.23 %, ce qui la place devant 13.2 % des CVE référencées.

Que faire ?

  • Vérifiez si Linux (versions <=6.1.*, <=6.12.*, 5.15.221, <34e88f53614640b59039a46717fb6142e9871022, ddf8abd2599491cbad959c700b90ba72a5dce8d0, 5.10.270, 0, <eac233e63f9db82ba874e3cccafaafab162999e0, 7.2.4, 6.1.188, <fbe3db4b650c284df8eb4cb68eebcf270cf861b5, <=5.10.*, <=6.6.*, 6.6.157, <fd20cc68bbdb5620696ac108e8f2efd180fe2c1a, <=6.18.*, <2.6.35, <=7.2.*, <=*, <b0a6bfac0c3c3edf5b2ecaee87a09234601fe78d, <=5.15.*, <bafddd0f20b5228760be303aa69c58502e92309c, <569dd7e5dcffe1e1c6b26ca2cd3be57eb433e082, 6.18.50, <30430509c156e1df2bdafd5f1cadb160e53db5d6, 6.12.109, 2.6.35, 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

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