kernel/linux.git/drivers/usb/gadget/function/f_midi.c, branch v6.6.150

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

2026-08-03T09:15:16+00:00

commit 5650c18d93a1db7e27cb5a40b394747eb4686d5b upstream. 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. Fixes: 8653d71ce3763 ("usb/gadget: f_midi: Replace tasklet with work") Cc: stable Assisted-by: Codex:gpt-5.5 Signed-off-by: Fan Wu Link: https://patch.msgid.link/20260709150717.399083-1-fanwu01@zju.edu.cn Signed-off-by: Greg Kroah-Hartman

USB: gadget: f_midi: f_midi_complete to call queue_work

2025-02-27T12:10:47+00:00

[ Upstream commit 4ab37fcb42832cdd3e9d5e50653285ca84d6686f ] When using USB MIDI, a lock is attempted to be acquired twice through a re-entrant call to f_midi_transmit, causing a deadlock. Fix it by using queue_work() to schedule the inner f_midi_transmit() via a high priority work queue from the completion handler. Link: https://lore.kernel.org/all/CAArt=LjxU0fUZOj06X+5tkeGT+6RbXzpWg1h4t4Fwa_KGVAX6g@mail.gmail.com/ Fixes: d5daf49b58661 ("USB: gadget: midi: add midi function driver") Cc: stable Signed-off-by: Jill Donahue Link: https://lore.kernel.org/r/20250211174805.1369265-1-jdonahue@fender.com Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sasha Levin

usb: gadget: f_midi: fix MIDI Streaming descriptor lengths

2025-02-21T12:57:15+00:00

commit da1668997052ed1cb00322e1f3b63702615c9429 upstream. While the MIDI jacks are configured correctly, and the MIDIStreaming endpoint descriptors are filled with the correct information, bNumEmbMIDIJack and bLength are set incorrectly in these descriptors. This does not matter when the numbers of in and out ports are equal, but when they differ the host will receive broken descriptors with uninitialized stack memory leaking into the descriptor for whichever value is smaller. The precise meaning of "in" and "out" in the port counts is not clearly defined and can be confusing. But elsewhere the driver consistently uses this to match the USB meaning of IN and OUT viewed from the host, so that "in" ports send data to the host and "out" ports receive data from it. Cc: stable Fixes: c8933c3f79568 ("USB: gadget: f_midi: allow a dynamic number of input and output ports") Signed-off-by: John Keeping Reviewed-by: Takashi Iwai Link: https://lore.kernel.org/r/20250130195035.3883857-1-jkeeping@inmusicbrands.com Signed-off-by: Greg Kroah-Hartman

usb: gadget: f_midi: Fixing wMaxPacketSize exceeded issue during MIDI bind retries

2025-02-21T12:57:13+00:00

commit 9e8b21410f310c50733f6e1730bae5a8e30d3570 upstream. The current implementation sets the wMaxPacketSize of bulk in/out endpoints to 1024 bytes at the end of the f_midi_bind function. However, in cases where there is a failure in the first midi bind attempt, consider rebinding. This scenario may encounter an f_midi_bind issue due to the previous bind setting the bulk endpoint's wMaxPacketSize to 1024 bytes, which exceeds the ep->maxpacket_limit where configured dwc3 TX/RX FIFO's maxpacket size of 512 bytes for IN/OUT endpoints in support HS speed only. Here the term "rebind" in this context refers to attempting to bind the MIDI function a second time in certain scenarios. The situations where rebinding is considered include: * When there is a failure in the first UDC write attempt, which may be caused by other functions bind along with MIDI. * Runtime composition change : Example : MIDI,ADB to MIDI. Or MIDI to MIDI,ADB. This commit addresses this issue by resetting the wMaxPacketSize before endpoint claim. And here there is no need to reset all values in the usb endpoint descriptor structure, as all members except wMaxPacketSize and bEndpointAddress have predefined values. This ensures that restores the endpoint to its expected configuration, and preventing conflicts with value of ep->maxpacket_limit. It also aligns with the approach used in other function drivers, which treat endpoint descriptors as if they were full speed before endpoint claim. Fixes: 46decc82ffd5 ("usb: gadget: unconditionally allocate hs/ss descriptor in bind operation") Cc: stable@vger.kernel.org Signed-off-by: Selvarasu Ganesan Link: https://lore.kernel.org/r/20250118060134.927-1-selvarasu.g@samsung.com Signed-off-by: Greg Kroah-Hartman

usb: gadget: unconditionally allocate hs/ss descriptor in bind operation

2023-08-22T12:48:33+00:00

Take f_midi_bind() for example, when composite layer call it, it will allocate hs descriptor by calling gadget_is_dualspeed() API to check gadget max support speed capability, but most other gadget function didn't do like this. To follow other function drivers, it is safe to remove the check which mean support all possible link speed by default in function driver. Similar change apply to midi2 and uvc. Also in midi and midi2, as there is no descriptor difference between super speed and super speed plus, follow other gadget function drivers, do not allocate descriptor for super speed plus, composite layer will handle it properly. Signed-off-by: Linyu Yuan Link: https://lore.kernel.org/r/20230803091053.9714-5-quic_linyyuan@quicinc.com Signed-off-by: Greg Kroah-Hartman

usb: gadget: f_midi: allow resetting index option

2021-11-17T13:40:43+00:00

Unlike the other integral options supported by the MIDI gadget, index is a signed integer and defaults to -1, which means "choose any sound card index". The generic store routine parses input into a u32 which fails to properly read -1 if an attempt is made to set the value to the default. Add a new macro block for signed values to fix this, and use the correct format string for unsigned values. Signed-off-by: John Keeping Link: https://lore.kernel.org/r/20211029134115.351008-1-john@metanate.com Signed-off-by: Greg Kroah-Hartman

usb/gadget: f_midi: Replace tasklet with work

2021-01-12T11:52:28+00:00

Currently a tasklet is used to transmit input substream buffer data. However, tasklets have long been deprecated as being too heavy on the system by running in irq context - and this is not a performance critical path. If a higher priority process wants to run, it must wait for the tasklet to finish before doing so. Deferring work to a workqueue and executing in process context should be fine considering the callback already does f_midi_do_transmit() under the transmit_lock and thus changes in semantics are ok regarding concurrency - tasklets being serialized against itself. Cc: Takashi Iwai Reviewed-by: Takashi Iwai Acked-by: Felipe Balbi Signed-off-by: Davidlohr Bueso Link: https://lore.kernel.org/r/20210111042855.73289-1-dave@stgolabs.net Signed-off-by: Greg Kroah-Hartman

USB: gadget: f_midi: setup SuperSpeed Plus descriptors

2020-12-10T15:12:23+00:00

Needed for SuperSpeed Plus support for f_midi. This allows the gadget to work properly without crashing at SuperSpeed rates. Cc: Felipe Balbi Cc: stable Signed-off-by: Will McVicker Reviewed-by: Peter Chen Link: https://lore.kernel.org/r/20201127140559.381351-4-gregkh@linuxfoundation.org Signed-off-by: Greg Kroah-Hartman

usb: gadget: f_midi: Fix memleak in f_midi_alloc

2020-11-20T15:32:42+00:00

In the error path, if midi is not null, we should free the midi->id if necessary to prevent memleak. Fixes: b85e9de9e818d ("usb: gadget: f_midi: convert to new function interface with backward compatibility") Reported-by: Hulk Robot Signed-off-by: Zhang Qilong Link: https://lore.kernel.org/r/20201117021629.1470544-2-zhangqilong3@huawei.com Cc: stable Signed-off-by: Greg Kroah-Hartman

usb/gadget: f_midi: convert tasklets to use new tasklet_setup() API

2020-08-18T11:00:01+00:00

In preparation for unconditionally passing the struct tasklet_struct pointer to all tasklet callbacks, switch to using the new tasklet_setup() and from_tasklet() to pass the tasklet pointer explicitly. Signed-off-by: Romain Perier Signed-off-by: Allen Pais Link: https://lore.kernel.org/r/20200817090209.26351-5-allen.cryptic@gmail.com Signed-off-by: Greg Kroah-Hartman