CVE-2026-64584

Description

In the Linux kernel, the following vulnerability has been resolved: usb: gadget: f_midi: cancel pending IN work before freeing the midi object The f_midi driver embeds a work item (midi->work) whose handler, f_midi_in_work(), dereferences the enclosing struct f_midi through container_of(). This work is armed from two sites: f_midi_complete(), on a normal IN-endpoint completion, and f_midi_in_trigger(), on an ALSA rawmidi output-stream start. Neither f_midi_disable() nor f_midi_unbind() cancels midi->work. f_midi_disable() only disables the endpoints and drains the in_req_fifo; it does not synchronize the work item, and the sound card is released asynchronously to the final free of the midi object. The midi object is reference-counted (midi->free_ref) and is freed in f_midi_free() only once both the usb_function reference and the rawmidi private_data reference have been dropped. In f_midi_unbind(), f_midi_disable() runs before the sound card is released, so while the USB endpoints are already disabled the rawmidi device is still usable by an open substream. A concurrent userspace write on such a substream can reach f_midi_in_trigger() and queue midi->work again after f_midi_disable() has returned. A work item armed this way may still be pending when the last reference drops and f_midi_free() proceeds to kfree(midi), letting f_midi_in_work() dereference the struct after it has been freed, a use-after-free. For this reason cancelling midi->work in f_midi_disable() would not be sufficient: the ALSA trigger path can rearm the work after disable() returns. Cancelling at the refcount-zero free site is the boundary after which neither arming source can survive, because by then both references that keep the midi object alive have been dropped: the USB endpoints are already disabled and the rawmidi device has been released. Fix this by calling cancel_work_sync(&midi->work) in the refcount-zero block of f_midi_free(), before the embedded work_struct is freed along with the rest of the structure. opts->lock is a sleeping mutex, so calling cancel_work_sync() under it is permitted, and the handler takes midi->transmit_lock rather than opts->lock, so no self-deadlock can occur while it waits for a running instance of the work to finish. This issue was found by an in-house static analysis tool.

Gravité et risque d'exploitation

CVE-2026-64584 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 0.12 %, ce qui la place devant 1.5 % des CVE référencées.

Que faire ?

• Vérifiez si Linux (versions <=6.1.*, <df18150126f66817e4d3f79f309e9c92d6ff384e, <=6.12.*, 6.12.101, <5.10.265, 0, <=7.1.*, <f45089eaad0a083d71d84ff175741d7e157d9b69, 5.15.216, <380b4bef46c2eb260c7a9c6bb2c5be33ce5a38f9, 5.12, <=5.10.*, <=6.6.*, 6.18.42, <620955b222c47332297d6bf38f78541aa699238a, <f3c6f2c38062703d3dc7f86958bb0790c6959add, 7.1.6, 6.1.183, <87bc316dd6fc90072297c635e10b9aa6075ecda1, <5.5, 5.4.291, 3635523e9b96213969693c320302d536774d8e9b, <=6.18.*, 89019ab7a64fcdf98a2ba7799e5c6aff58d4a05d, <5650c18d93a1db7e27cb5a40b394747eb4686d5b, <5.12, 8653d71ce3763aedcf3d2331f59beda3fecd79e4, <=*, <=5.15.*, 5.10.235, 5.10.265, 6.6.148, 7.2, <ac9a51d910bb7465c554c45320cb6c09f3d0b49d) 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/f3c6f2c38062703d3dc7f86958bb0790c6959add
• https://git.kernel.org/stable/c/df18150126f66817e4d3f79f309e9c92d6ff384e
• https://git.kernel.org/stable/c/620955b222c47332297d6bf38f78541aa699238a
• https://git.kernel.org/stable/c/380b4bef46c2eb260c7a9c6bb2c5be33ce5a38f9
• https://git.kernel.org/stable/c/87bc316dd6fc90072297c635e10b9aa6075ecda1
• https://git.kernel.org/stable/c/f45089eaad0a083d71d84ff175741d7e157d9b69
• https://git.kernel.org/stable/c/ac9a51d910bb7465c554c45320cb6c09f3d0b49d
• https://git.kernel.org/stable/c/5650c18d93a1db7e27cb5a40b394747eb4686d5b