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CVE PROGRAM SOURCE RECORD7.8 High

CVE-2026-64584

usb: gadget: f_midi: cancel pending IN work before freeing the midi object

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Status
Published
Published
Updated
Assigning organization
Linux

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.

Affected products

Version statuses are supplied by the assigning organization. Consult the original record for detailed ranges and platform conditions.

Linux Linux

Default version status: unaffected

  • 3635523e9b96213969693c320302d536774d8e9b to < f3c6f2c38062703d3dc7f86958bb0790c6959addaffected
  • 8653d71ce3763aedcf3d2331f59beda3fecd79e4 to < df18150126f66817e4d3f79f309e9c92d6ff384eaffected
  • 8653d71ce3763aedcf3d2331f59beda3fecd79e4 to < 620955b222c47332297d6bf38f78541aa699238aaffected
  • 8653d71ce3763aedcf3d2331f59beda3fecd79e4 to < 380b4bef46c2eb260c7a9c6bb2c5be33ce5a38f9affected
  • 8653d71ce3763aedcf3d2331f59beda3fecd79e4 to < 87bc316dd6fc90072297c635e10b9aa6075ecda1affected
  • 8653d71ce3763aedcf3d2331f59beda3fecd79e4 to < f45089eaad0a083d71d84ff175741d7e157d9b69affected
  • 8653d71ce3763aedcf3d2331f59beda3fecd79e4 to < ac9a51d910bb7465c554c45320cb6c09f3d0b49daffected
  • 8653d71ce3763aedcf3d2331f59beda3fecd79e4 to < 5650c18d93a1db7e27cb5a40b394747eb4686d5baffected
  • 89019ab7a64fcdf98a2ba7799e5c6aff58d4a05daffected
  • 5.10.235 to < 5.10.265affected
  • 5.4.291 to < 5.5affected

Linux Linux

Default version status: affected

  • 5.12affected
  • 0 to < 5.12unaffected
  • 5.10.265 to ≤ 5.10.*unaffected
  • 5.15.216 to ≤ 5.15.*unaffected
  • 6.1.183 to ≤ 6.1.*unaffected
  • 6.6.148 to ≤ 6.6.*unaffected
  • 6.12.101 to ≤ 6.12.*unaffected
  • 6.18.42 to ≤ 6.18.*unaffected
  • 7.1.6 to ≤ 7.1.*unaffected
  • 7.2 to ≤ *unaffected

References