CVE-2026-64584 is a vulnerability in Linux Kernel
Published on August 6, 2026
usb: gadget: f_midi: cancel pending IN work before freeing the midi object
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.
Products Associated with CVE-2026-64584
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Affected Versions
Linux:- Version 8653d71ce3763aedcf3d2331f59beda3fecd79e4 and below 380b4bef46c2eb260c7a9c6bb2c5be33ce5a38f9 is affected.
- Version 8653d71ce3763aedcf3d2331f59beda3fecd79e4 and below 87bc316dd6fc90072297c635e10b9aa6075ecda1 is affected.
- Version 8653d71ce3763aedcf3d2331f59beda3fecd79e4 and below f45089eaad0a083d71d84ff175741d7e157d9b69 is affected.
- Version 8653d71ce3763aedcf3d2331f59beda3fecd79e4 and below ac9a51d910bb7465c554c45320cb6c09f3d0b49d is affected.
- Version 8653d71ce3763aedcf3d2331f59beda3fecd79e4 and below 5650c18d93a1db7e27cb5a40b394747eb4686d5b is affected.
- Version 89019ab7a64fcdf98a2ba7799e5c6aff58d4a05d is affected.
- Version 3635523e9b96213969693c320302d536774d8e9b is affected.
- Version 5.4.291 and below 5.5 is affected.
- Version 5.10.235 and below 5.11 is affected.
- Version 5.12 is affected.
- Before 5.12 is unaffected.
- Version 6.6.148, <= 6.6.* is unaffected.
- Version 6.12.101, <= 6.12.* is unaffected.
- Version 6.18.42, <= 6.18.* is unaffected.
- Version 7.1.6, <= 7.1.* is unaffected.
- Version 7.2-rc5, <= * is unaffected.