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usb: gadget: f_midi: fix MIDI Streaming descriptor lengths

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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 <stable@kernel.org>
Fixes: c8933c3f79 ("USB: gadget: f_midi: allow a dynamic number of input and output ports")
Signed-off-by: John Keeping <jkeeping@inmusicbrands.com>
Reviewed-by: Takashi Iwai <tiwai@suse.de>
Link: https://lore.kernel.org/r/20250130195035.3883857-1-jkeeping@inmusicbrands.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
John Keeping 2025-01-30 19:50:34 +00:00 • committed by Greg Kroah-Hartman
parent 58cd423820
commit da16689970
1 changed files with 4 additions and 4 deletions
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8
drivers/usb/gadget/function/f_midi.c
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@ -1009,11 +1009,11 @@ static int f_midi_bind(struct usb_configuration *c, struct usb_function *f)
}
/* configure the endpoint descriptors ... */
ms_out_desc.bLength = USB_DT_MS_ENDPOINT_SIZE(midi->in_ports);
ms_out_desc.bNumEmbMIDIJack = midi->in_ports;
ms_out_desc.bLength = USB_DT_MS_ENDPOINT_SIZE(midi->out_ports);
ms_out_desc.bNumEmbMIDIJack = midi->out_ports;
ms_in_desc.bLength = USB_DT_MS_ENDPOINT_SIZE(midi->out_ports);
ms_in_desc.bNumEmbMIDIJack = midi->out_ports;
ms_in_desc.bLength = USB_DT_MS_ENDPOINT_SIZE(midi->in_ports);
ms_in_desc.bNumEmbMIDIJack = midi->in_ports;
/* ... and add them to the list */
endpoint_descriptor_index = i;