linux.git/drivers/usb/gadget/function/f_midi.c, branch master

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

2026-07-13T05:10:11+00:00

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

Convert more 'alloc_obj' cases to default GFP_KERNEL arguments

2026-02-22T04:03:00+00:00

This converts some of the visually simpler cases that have been split over multiple lines. I only did the ones that are easy to verify the resulting diff by having just that final GFP_KERNEL argument on the next line. Somebody should probably do a proper coccinelle script for this, but for me the trivial script actually resulted in an assertion failure in the middle of the script. I probably had made it a bit _too_ trivial. So after fighting that far a while I decided to just do some of the syntactically simpler cases with variations of the previous 'sed' scripts. The more syntactically complex multi-line cases would mostly really want whitespace cleanup anyway. Signed-off-by: Linus Torvalds

Convert 'alloc_flex' family to use the new default GFP_KERNEL argument

2026-02-22T01:09:51+00:00

This is the exact same thing as the 'alloc_obj()' version, only much smaller because there are a lot fewer users of the *alloc_flex() interface. As with alloc_obj() version, this was done entirely with mindless brute force, using the same script, except using 'flex' in the pattern rather than 'objs*'. Signed-off-by: Linus Torvalds

Convert 'alloc_obj' family to use the new default GFP_KERNEL argument

2026-02-22T01:09:51+00:00

This was done entirely with mindless brute force, using git grep -l '\

treewide: Replace kmalloc with kmalloc_obj for non-scalar types

2026-02-21T09:02:28+00:00

This is the result of running the Coccinelle script from scripts/coccinelle/api/kmalloc_objs.cocci. The script is designed to avoid scalar types (which need careful case-by-case checking), and instead replace kmalloc-family calls that allocate struct or union object instances: Single allocations: kmalloc(sizeof(TYPE), ...) are replaced with: kmalloc_obj(TYPE, ...) Array allocations: kmalloc_array(COUNT, sizeof(TYPE), ...) are replaced with: kmalloc_objs(TYPE, COUNT, ...) Flex array allocations: kmalloc(struct_size(PTR, FAM, COUNT), ...) are replaced with: kmalloc_flex(*PTR, FAM, COUNT, ...) (where TYPE may also be *VAR) The resulting allocations no longer return "void *", instead returning "TYPE *". Signed-off-by: Kees Cook

usb: gadget: Constify struct configfs_item_operations and configfs_group_operations

2025-12-23T14:31:01+00:00

'struct configfs_item_operations' and 'configfs_group_operations' are not modified in these drivers. Constifying these structures moves some data to a read-only section, so increases overall security, especially when the structure holds some function pointers. On a x86_64, with allmodconfig, as an example: Before: ====== text data bss dec hex filename 65061 20968 256 86285 1510d drivers/usb/gadget/configfs.o After: ===== text data bss dec hex filename 66181 19848 256 86285 1510d drivers/usb/gadget/configfs.o Signed-off-by: Christophe JAILLET Link: https://patch.msgid.link/49cec1cb84425f854de80b6d69b53a5a3cda8189.1766164523.git.christophe.jaillet@wanadoo.fr Signed-off-by: Greg Kroah-Hartman

usb: gadget: f_midi: allow customizing the USB MIDI interface string through configfs

2025-12-17T13:43:01+00:00

When using f_midi from configfs the USB MIDI interface string is hardcoded to 'MIDI function'. This USB string descriptor is used by some third-party OS or software to display the name of the MIDI device Since we add an additional string option a new macro block was created to factorize declarations Signed-off-by: Victor Krawiec Reviewed-by: Takashi Iwai Link: https://patch.msgid.link/20251209164006.143219-1-victor.krawiec@arturia.com Signed-off-by: Greg Kroah-Hartman

USB: gadget: f_midi: f_midi_complete to call queue_work

2025-02-14T08:24:20+00:00

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

usb: gadget: f_midi: fix MIDI Streaming descriptor lengths

2025-02-03T15:42:22+00:00

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

2025-02-03T15:39:32+00:00

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