[PATCH] usb: gadget: f_midi: fix MIDI Streaming descriptor lengths

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* [PATCH] usb: gadget: f_midi: fix MIDI Streaming descriptor lengths
@ 2025-01-29 16:05 John Keeping
  2025-01-29 16:40 ` Takashi Iwai
  0 siblings, 1 reply; 7+ messages in thread
From: John Keeping @ 2025-01-29 16:05 UTC (permalink / raw)
  To: linux-usb
  Cc: John Keeping, stable, Greg Kroah-Hartman, Kees Cook, Abdul Rahim,
	Michael Grzeschik, Jeff Johnson, Felipe Balbi, Daniel Mack,
	linux-kernel

In the two loops before setting the MIDIStreaming descriptors,
ms_in_desc.baAssocJackID[] has entries written for "in_ports" values and
ms_out_desc.baAssocJackID[] has entries written for "out_ports" values.
But the counts and lengths are set the other way round in the
descriptors.

Fix the descriptors so that the bNumEmbMIDIJack values and the
descriptor lengths match the number of entries populated in the trailing
arrays.

Cc: stable@vger.kernel.org
Fixes: c8933c3f79568 ("USB: gadget: f_midi: allow a dynamic number of input and output ports")
Signed-off-by: John Keeping <jkeeping@inmusicbrands.com>
---
 drivers/usb/gadget/function/f_midi.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/usb/gadget/function/f_midi.c b/drivers/usb/gadget/function/f_midi.c
index 837fcdfa3840f..6cc3d86cb4774 100644
--- a/drivers/usb/gadget/function/f_midi.c
+++ b/drivers/usb/gadget/function/f_midi.c
@@ -1000,11 +1000,11 @@ 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;
-- 
2.48.1


^ permalink raw reply related	[flat|nested] 7+ messages in thread

* Re: [PATCH] usb: gadget: f_midi: fix MIDI Streaming descriptor lengths
  2025-01-29 16:05 [PATCH] usb: gadget: f_midi: fix MIDI Streaming descriptor lengths John Keeping
@ 2025-01-29 16:40 ` Takashi Iwai
  2025-01-29 17:31   ` John Keeping
  0 siblings, 1 reply; 7+ messages in thread
From: Takashi Iwai @ 2025-01-29 16:40 UTC (permalink / raw)
  To: John Keeping
  Cc: linux-usb, stable, Greg Kroah-Hartman, Kees Cook, Abdul Rahim,
	Michael Grzeschik, Jeff Johnson, Felipe Balbi, Daniel Mack,
	linux-kernel

On Wed, 29 Jan 2025 17:05:19 +0100,
John Keeping wrote:
> 
> In the two loops before setting the MIDIStreaming descriptors,
> ms_in_desc.baAssocJackID[] has entries written for "in_ports" values and
> ms_out_desc.baAssocJackID[] has entries written for "out_ports" values.
> But the counts and lengths are set the other way round in the
> descriptors.
> 
> Fix the descriptors so that the bNumEmbMIDIJack values and the
> descriptor lengths match the number of entries populated in the trailing
> arrays.

Are you sure that it's a correct change?

IIUC, the in_ports and out_ports parameters are for external IN and
OUT jacks, where an external OUT jack is connected to an embedded IN
jack, and an external IN jack is connected to an embedded OUT jack.


thanks,

Takashi

> 
> Cc: stable@vger.kernel.org
> Fixes: c8933c3f79568 ("USB: gadget: f_midi: allow a dynamic number of input and output ports")
> Signed-off-by: John Keeping <jkeeping@inmusicbrands.com>
> ---
>  drivers/usb/gadget/function/f_midi.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/usb/gadget/function/f_midi.c b/drivers/usb/gadget/function/f_midi.c
> index 837fcdfa3840f..6cc3d86cb4774 100644
> --- a/drivers/usb/gadget/function/f_midi.c
> +++ b/drivers/usb/gadget/function/f_midi.c
> @@ -1000,11 +1000,11 @@ 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;
> -- 
> 2.48.1
> 
> 

^ permalink raw reply	[flat|nested] 7+ messages in thread

* Re: [PATCH] usb: gadget: f_midi: fix MIDI Streaming descriptor lengths
  2025-01-29 16:40 ` Takashi Iwai
@ 2025-01-29 17:31   ` John Keeping
  2025-01-30 10:50     ` Takashi Iwai
  0 siblings, 1 reply; 7+ messages in thread
From: John Keeping @ 2025-01-29 17:31 UTC (permalink / raw)
  To: Takashi Iwai
  Cc: linux-usb, stable, Greg Kroah-Hartman, Kees Cook, Abdul Rahim,
	Michael Grzeschik, Jeff Johnson, Felipe Balbi, Daniel Mack,
	linux-kernel

On Wed, Jan 29, 2025 at 05:40:04PM +0100, Takashi Iwai wrote:
> On Wed, 29 Jan 2025 17:05:19 +0100,
> John Keeping wrote:
> > 
> > In the two loops before setting the MIDIStreaming descriptors,
> > ms_in_desc.baAssocJackID[] has entries written for "in_ports" values and
> > ms_out_desc.baAssocJackID[] has entries written for "out_ports" values.
> > But the counts and lengths are set the other way round in the
> > descriptors.
> > 
> > Fix the descriptors so that the bNumEmbMIDIJack values and the
> > descriptor lengths match the number of entries populated in the trailing
> > arrays.
> 
> Are you sure that it's a correct change?
> 
> IIUC, the in_ports and out_ports parameters are for external IN and
> OUT jacks, where an external OUT jack is connected to an embedded IN
> jack, and an external IN jack is connected to an embedded OUT jack.

I think it depends how the in_ports and out_ports values in configfs are
interpreted.  However, the case where in_ports != out_ports has been
broken since these files were added!

Without this change, setting in_ports=4 out_ports=2 we end up with:

      Endpoint Descriptor:
        [...]
        bEndpointAddress     0x01  EP 1 OUT
        [...]
        MIDIStreaming Endpoint Descriptor:
          bLength                 8
          bDescriptorType        37
          bDescriptorSubtype      1 (Invalid)
          bNumEmbMIDIJack         4
          baAssocJackID( 0)       9
          baAssocJackID( 1)      11
          baAssocJackID( 2)       9
          baAssocJackID( 3)       0
      Endpoint Descriptor:
        [...]
        bEndpointAddress     0x81  EP 1 IN
        [...]
        MIDIStreaming Endpoint Descriptor:
          bLength                 6
          bDescriptorType        37
          bDescriptorSubtype      1 (Invalid)
          bNumEmbMIDIJack         2
          baAssocJackID( 0)       2
          baAssocJackID( 1)       4

Note that baAssocJackID values 2 and 3 on the OUT endpoint are wrong.

From the same config, the jack definitions are:

	1:  IN  External
	2:  OUT Embedded, source 1
	3:  IN  External
	4:  OUT Embedded, source 3
	5:  IN  External
	6:  OUT Embedded, source 5
	7:  IN  External
	8:  OUT Embedded, source 7

	9:  IN  Embedded
	10: OUT External, source 9
	11: IN  Embedded
	12: OUT External, source 11

So it seems that the first 2 entries in each endpoint list are correct.
For the OUT endpoint, jacks 9 and 11 are embedded IN jacks and for the
IN endpoint, jacks 2 and 4 are embedded OUT jacks.

The problem is that the OUT endpoint lists two extra invalid jack IDs
and the IN endpoint should list jacks 6 and 8 but does not.

After applying this patch, the endpoint descriptors for the same config
are:

      Endpoint Descriptor:
        [...]
        bEndpointAddress     0x01  EP 1 OUT
        [...]
        MIDIStreaming Endpoint Descriptor:
          bLength                 6
          bDescriptorType        37
          bDescriptorSubtype      1 (Invalid)
          bNumEmbMIDIJack         2
          baAssocJackID( 0)       9
          baAssocJackID( 1)      11
      Endpoint Descriptor:
        [...]
        bEndpointAddress     0x81  EP 1 IN
        [...]
        MIDIStreaming Endpoint Descriptor:
          bLength                 8
          bDescriptorType        37
          bDescriptorSubtype      1 (Invalid)
          bNumEmbMIDIJack         4
          baAssocJackID( 0)       2
          baAssocJackID( 1)       4
          baAssocJackID( 2)       6
          baAssocJackID( 3)       8

Which lists all the jack IDs where they should be.


Regards,
John

> > Cc: stable@vger.kernel.org
> > Fixes: c8933c3f79568 ("USB: gadget: f_midi: allow a dynamic number of input and output ports")
> > Signed-off-by: John Keeping <jkeeping@inmusicbrands.com>
> > ---
> >  drivers/usb/gadget/function/f_midi.c | 8 ++++----
> >  1 file changed, 4 insertions(+), 4 deletions(-)
> > 
> > diff --git a/drivers/usb/gadget/function/f_midi.c b/drivers/usb/gadget/function/f_midi.c
> > index 837fcdfa3840f..6cc3d86cb4774 100644
> > --- a/drivers/usb/gadget/function/f_midi.c
> > +++ b/drivers/usb/gadget/function/f_midi.c
> > @@ -1000,11 +1000,11 @@ 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;
> > -- 
> > 2.48.1
> > 
> > 

^ permalink raw reply	[flat|nested] 7+ messages in thread

* Re: [PATCH] usb: gadget: f_midi: fix MIDI Streaming descriptor lengths
  2025-01-29 17:31   ` John Keeping
@ 2025-01-30 10:50     ` Takashi Iwai
  2025-01-30 10:59       ` John Keeping
  0 siblings, 1 reply; 7+ messages in thread
From: Takashi Iwai @ 2025-01-30 10:50 UTC (permalink / raw)
  To: John Keeping
  Cc: Takashi Iwai, linux-usb, stable, Greg Kroah-Hartman, Kees Cook,
	Abdul Rahim, Michael Grzeschik, Jeff Johnson, Felipe Balbi,
	Daniel Mack, linux-kernel

On Wed, 29 Jan 2025 18:31:35 +0100,
John Keeping wrote:
> 
> On Wed, Jan 29, 2025 at 05:40:04PM +0100, Takashi Iwai wrote:
> > On Wed, 29 Jan 2025 17:05:19 +0100,
> > John Keeping wrote:
> > > 
> > > In the two loops before setting the MIDIStreaming descriptors,
> > > ms_in_desc.baAssocJackID[] has entries written for "in_ports" values and
> > > ms_out_desc.baAssocJackID[] has entries written for "out_ports" values.
> > > But the counts and lengths are set the other way round in the
> > > descriptors.
> > > 
> > > Fix the descriptors so that the bNumEmbMIDIJack values and the
> > > descriptor lengths match the number of entries populated in the trailing
> > > arrays.
> > 
> > Are you sure that it's a correct change?
> > 
> > IIUC, the in_ports and out_ports parameters are for external IN and
> > OUT jacks, where an external OUT jack is connected to an embedded IN
> > jack, and an external IN jack is connected to an embedded OUT jack.
> 
> I think it depends how the in_ports and out_ports values in configfs are
> interpreted.  However, the case where in_ports != out_ports has been
> broken since these files were added!
> 
> Without this change, setting in_ports=4 out_ports=2 we end up with:
> 
>       Endpoint Descriptor:
>         [...]
>         bEndpointAddress     0x01  EP 1 OUT
>         [...]
>         MIDIStreaming Endpoint Descriptor:
>           bLength                 8
>           bDescriptorType        37
>           bDescriptorSubtype      1 (Invalid)
>           bNumEmbMIDIJack         4
>           baAssocJackID( 0)       9
>           baAssocJackID( 1)      11
>           baAssocJackID( 2)       9
>           baAssocJackID( 3)       0
>       Endpoint Descriptor:
>         [...]
>         bEndpointAddress     0x81  EP 1 IN
>         [...]
>         MIDIStreaming Endpoint Descriptor:
>           bLength                 6
>           bDescriptorType        37
>           bDescriptorSubtype      1 (Invalid)
>           bNumEmbMIDIJack         2
>           baAssocJackID( 0)       2
>           baAssocJackID( 1)       4
> 
> Note that baAssocJackID values 2 and 3 on the OUT endpoint are wrong.
> 
> From the same config, the jack definitions are:
> 
> 	1:  IN  External
> 	2:  OUT Embedded, source 1
> 	3:  IN  External
> 	4:  OUT Embedded, source 3
> 	5:  IN  External
> 	6:  OUT Embedded, source 5
> 	7:  IN  External
> 	8:  OUT Embedded, source 7
> 
> 	9:  IN  Embedded
> 	10: OUT External, source 9
> 	11: IN  Embedded
> 	12: OUT External, source 11
> 
> So it seems that the first 2 entries in each endpoint list are correct.
> For the OUT endpoint, jacks 9 and 11 are embedded IN jacks and for the
> IN endpoint, jacks 2 and 4 are embedded OUT jacks.
> 
> The problem is that the OUT endpoint lists two extra invalid jack IDs
> and the IN endpoint should list jacks 6 and 8 but does not.
> 
> After applying this patch, the endpoint descriptors for the same config
> are:
> 
>       Endpoint Descriptor:
>         [...]
>         bEndpointAddress     0x01  EP 1 OUT
>         [...]
>         MIDIStreaming Endpoint Descriptor:
>           bLength                 6
>           bDescriptorType        37
>           bDescriptorSubtype      1 (Invalid)
>           bNumEmbMIDIJack         2
>           baAssocJackID( 0)       9
>           baAssocJackID( 1)      11
>       Endpoint Descriptor:
>         [...]
>         bEndpointAddress     0x81  EP 1 IN
>         [...]
>         MIDIStreaming Endpoint Descriptor:
>           bLength                 8
>           bDescriptorType        37
>           bDescriptorSubtype      1 (Invalid)
>           bNumEmbMIDIJack         4
>           baAssocJackID( 0)       2
>           baAssocJackID( 1)       4
>           baAssocJackID( 2)       6
>           baAssocJackID( 3)       8
> 
> Which lists all the jack IDs where they should be.

Hmm, I don't get your point.  The embedded IN is paired with the
external OUT.  That's the intended behavior, no?


Takashi

> 
> 
> Regards,
> John
> 
> > > Cc: stable@vger.kernel.org
> > > Fixes: c8933c3f79568 ("USB: gadget: f_midi: allow a dynamic number of input and output ports")
> > > Signed-off-by: John Keeping <jkeeping@inmusicbrands.com>
> > > ---
> > >  drivers/usb/gadget/function/f_midi.c | 8 ++++----
> > >  1 file changed, 4 insertions(+), 4 deletions(-)
> > > 
> > > diff --git a/drivers/usb/gadget/function/f_midi.c b/drivers/usb/gadget/function/f_midi.c
> > > index 837fcdfa3840f..6cc3d86cb4774 100644
> > > --- a/drivers/usb/gadget/function/f_midi.c
> > > +++ b/drivers/usb/gadget/function/f_midi.c
> > > @@ -1000,11 +1000,11 @@ 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;
> > > -- 
> > > 2.48.1
> > > 
> > > 

^ permalink raw reply	[flat|nested] 7+ messages in thread

* Re: [PATCH] usb: gadget: f_midi: fix MIDI Streaming descriptor lengths
  2025-01-30 10:50     ` Takashi Iwai
@ 2025-01-30 10:59       ` John Keeping
  2025-01-30 12:17         ` Takashi Iwai
  0 siblings, 1 reply; 7+ messages in thread
From: John Keeping @ 2025-01-30 10:59 UTC (permalink / raw)
  To: Takashi Iwai
  Cc: linux-usb, stable, Greg Kroah-Hartman, Kees Cook, Abdul Rahim,
	Michael Grzeschik, Jeff Johnson, Felipe Balbi, Daniel Mack,
	linux-kernel

On Thu, Jan 30, 2025 at 11:50:07AM +0100, Takashi Iwai wrote:
> On Wed, 29 Jan 2025 18:31:35 +0100,
> John Keeping wrote:
> > 
> > On Wed, Jan 29, 2025 at 05:40:04PM +0100, Takashi Iwai wrote:
> > > On Wed, 29 Jan 2025 17:05:19 +0100,
> > > John Keeping wrote:
> > > > 
> > > > In the two loops before setting the MIDIStreaming descriptors,
> > > > ms_in_desc.baAssocJackID[] has entries written for "in_ports" values and
> > > > ms_out_desc.baAssocJackID[] has entries written for "out_ports" values.
> > > > But the counts and lengths are set the other way round in the
> > > > descriptors.
> > > > 
> > > > Fix the descriptors so that the bNumEmbMIDIJack values and the
> > > > descriptor lengths match the number of entries populated in the trailing
> > > > arrays.
> > > 
> > > Are you sure that it's a correct change?
> > > 
> > > IIUC, the in_ports and out_ports parameters are for external IN and
> > > OUT jacks, where an external OUT jack is connected to an embedded IN
> > > jack, and an external IN jack is connected to an embedded OUT jack.
> > 
> > I think it depends how the in_ports and out_ports values in configfs are
> > interpreted.  However, the case where in_ports != out_ports has been
> > broken since these files were added!
> > 
> > Without this change, setting in_ports=4 out_ports=2 we end up with:
> > 
> >       Endpoint Descriptor:
> >         [...]
> >         bEndpointAddress     0x01  EP 1 OUT
> >         [...]
> >         MIDIStreaming Endpoint Descriptor:
> >           bLength                 8
> >           bDescriptorType        37
> >           bDescriptorSubtype      1 (Invalid)
> >           bNumEmbMIDIJack         4
> >           baAssocJackID( 0)       9
> >           baAssocJackID( 1)      11
> >           baAssocJackID( 2)       9
> >           baAssocJackID( 3)       0
> >       Endpoint Descriptor:
> >         [...]
> >         bEndpointAddress     0x81  EP 1 IN
> >         [...]
> >         MIDIStreaming Endpoint Descriptor:
> >           bLength                 6
> >           bDescriptorType        37
> >           bDescriptorSubtype      1 (Invalid)
> >           bNumEmbMIDIJack         2
> >           baAssocJackID( 0)       2
> >           baAssocJackID( 1)       4
> > 
> > Note that baAssocJackID values 2 and 3 on the OUT endpoint are wrong.
> > 
> > From the same config, the jack definitions are:
> > 
> > 	1:  IN  External
> > 	2:  OUT Embedded, source 1
> > 	3:  IN  External
> > 	4:  OUT Embedded, source 3
> > 	5:  IN  External
> > 	6:  OUT Embedded, source 5
> > 	7:  IN  External
> > 	8:  OUT Embedded, source 7
> > 
> > 	9:  IN  Embedded
> > 	10: OUT External, source 9
> > 	11: IN  Embedded
> > 	12: OUT External, source 11
> > 
> > So it seems that the first 2 entries in each endpoint list are correct.
> > For the OUT endpoint, jacks 9 and 11 are embedded IN jacks and for the
> > IN endpoint, jacks 2 and 4 are embedded OUT jacks.
> > 
> > The problem is that the OUT endpoint lists two extra invalid jack IDs
> > and the IN endpoint should list jacks 6 and 8 but does not.
> > 
> > After applying this patch, the endpoint descriptors for the same config
> > are:
> > 
> >       Endpoint Descriptor:
> >         [...]
> >         bEndpointAddress     0x01  EP 1 OUT
> >         [...]
> >         MIDIStreaming Endpoint Descriptor:
> >           bLength                 6
> >           bDescriptorType        37
> >           bDescriptorSubtype      1 (Invalid)
> >           bNumEmbMIDIJack         2
> >           baAssocJackID( 0)       9
> >           baAssocJackID( 1)      11
> >       Endpoint Descriptor:
> >         [...]
> >         bEndpointAddress     0x81  EP 1 IN
> >         [...]
> >         MIDIStreaming Endpoint Descriptor:
> >           bLength                 8
> >           bDescriptorType        37
> >           bDescriptorSubtype      1 (Invalid)
> >           bNumEmbMIDIJack         4
> >           baAssocJackID( 0)       2
> >           baAssocJackID( 1)       4
> >           baAssocJackID( 2)       6
> >           baAssocJackID( 3)       8
> > 
> > Which lists all the jack IDs where they should be.
> 
> Hmm, I don't get your point.  The embedded IN is paired with the
> external OUT.  That's the intended behavior, no?

Yes, all the endpoint assignments are correct - when they appear in the
lists!

The issue is setting bNumEmbMIDIJack and bLength in the MIDIStreaming
Endpoint Descriptors.  Without this patch these are set the wrong way
round so either some ports do not appear or there are bogus entries
containing uninitialized stack memory.



Regards,
John

> > > > Cc: stable@vger.kernel.org
> > > > Fixes: c8933c3f79568 ("USB: gadget: f_midi: allow a dynamic number of input and output ports")
> > > > Signed-off-by: John Keeping <jkeeping@inmusicbrands.com>
> > > > ---
> > > >  drivers/usb/gadget/function/f_midi.c | 8 ++++----
> > > >  1 file changed, 4 insertions(+), 4 deletions(-)
> > > > 
> > > > diff --git a/drivers/usb/gadget/function/f_midi.c b/drivers/usb/gadget/function/f_midi.c
> > > > index 837fcdfa3840f..6cc3d86cb4774 100644
> > > > --- a/drivers/usb/gadget/function/f_midi.c
> > > > +++ b/drivers/usb/gadget/function/f_midi.c
> > > > @@ -1000,11 +1000,11 @@ 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;
> > > > -- 
> > > > 2.48.1
> > > > 
> > > > 

^ permalink raw reply	[flat|nested] 7+ messages in thread

* Re: [PATCH] usb: gadget: f_midi: fix MIDI Streaming descriptor lengths
  2025-01-30 10:59       ` John Keeping
@ 2025-01-30 12:17         ` Takashi Iwai
  2025-01-30 17:10           ` John Keeping
  0 siblings, 1 reply; 7+ messages in thread
From: Takashi Iwai @ 2025-01-30 12:17 UTC (permalink / raw)
  To: John Keeping
  Cc: Takashi Iwai, linux-usb, stable, Greg Kroah-Hartman, Kees Cook,
	Abdul Rahim, Michael Grzeschik, Jeff Johnson, Felipe Balbi,
	Daniel Mack, linux-kernel

On Thu, 30 Jan 2025 11:59:05 +0100,
John Keeping wrote:
> 
> On Thu, Jan 30, 2025 at 11:50:07AM +0100, Takashi Iwai wrote:
> > On Wed, 29 Jan 2025 18:31:35 +0100,
> > John Keeping wrote:
> > > 
> > > On Wed, Jan 29, 2025 at 05:40:04PM +0100, Takashi Iwai wrote:
> > > > On Wed, 29 Jan 2025 17:05:19 +0100,
> > > > John Keeping wrote:
> > > > > 
> > > > > In the two loops before setting the MIDIStreaming descriptors,
> > > > > ms_in_desc.baAssocJackID[] has entries written for "in_ports" values and
> > > > > ms_out_desc.baAssocJackID[] has entries written for "out_ports" values.
> > > > > But the counts and lengths are set the other way round in the
> > > > > descriptors.
> > > > > 
> > > > > Fix the descriptors so that the bNumEmbMIDIJack values and the
> > > > > descriptor lengths match the number of entries populated in the trailing
> > > > > arrays.
> > > > 
> > > > Are you sure that it's a correct change?
> > > > 
> > > > IIUC, the in_ports and out_ports parameters are for external IN and
> > > > OUT jacks, where an external OUT jack is connected to an embedded IN
> > > > jack, and an external IN jack is connected to an embedded OUT jack.
> > > 
> > > I think it depends how the in_ports and out_ports values in configfs are
> > > interpreted.  However, the case where in_ports != out_ports has been
> > > broken since these files were added!
> > > 
> > > Without this change, setting in_ports=4 out_ports=2 we end up with:
> > > 
> > >       Endpoint Descriptor:
> > >         [...]
> > >         bEndpointAddress     0x01  EP 1 OUT
> > >         [...]
> > >         MIDIStreaming Endpoint Descriptor:
> > >           bLength                 8
> > >           bDescriptorType        37
> > >           bDescriptorSubtype      1 (Invalid)
> > >           bNumEmbMIDIJack         4
> > >           baAssocJackID( 0)       9
> > >           baAssocJackID( 1)      11
> > >           baAssocJackID( 2)       9
> > >           baAssocJackID( 3)       0
> > >       Endpoint Descriptor:
> > >         [...]
> > >         bEndpointAddress     0x81  EP 1 IN
> > >         [...]
> > >         MIDIStreaming Endpoint Descriptor:
> > >           bLength                 6
> > >           bDescriptorType        37
> > >           bDescriptorSubtype      1 (Invalid)
> > >           bNumEmbMIDIJack         2
> > >           baAssocJackID( 0)       2
> > >           baAssocJackID( 1)       4
> > > 
> > > Note that baAssocJackID values 2 and 3 on the OUT endpoint are wrong.
> > > 
> > > From the same config, the jack definitions are:
> > > 
> > > 	1:  IN  External
> > > 	2:  OUT Embedded, source 1
> > > 	3:  IN  External
> > > 	4:  OUT Embedded, source 3
> > > 	5:  IN  External
> > > 	6:  OUT Embedded, source 5
> > > 	7:  IN  External
> > > 	8:  OUT Embedded, source 7
> > > 
> > > 	9:  IN  Embedded
> > > 	10: OUT External, source 9
> > > 	11: IN  Embedded
> > > 	12: OUT External, source 11
> > > 
> > > So it seems that the first 2 entries in each endpoint list are correct.
> > > For the OUT endpoint, jacks 9 and 11 are embedded IN jacks and for the
> > > IN endpoint, jacks 2 and 4 are embedded OUT jacks.
> > > 
> > > The problem is that the OUT endpoint lists two extra invalid jack IDs
> > > and the IN endpoint should list jacks 6 and 8 but does not.
> > > 
> > > After applying this patch, the endpoint descriptors for the same config
> > > are:
> > > 
> > >       Endpoint Descriptor:
> > >         [...]
> > >         bEndpointAddress     0x01  EP 1 OUT
> > >         [...]
> > >         MIDIStreaming Endpoint Descriptor:
> > >           bLength                 6
> > >           bDescriptorType        37
> > >           bDescriptorSubtype      1 (Invalid)
> > >           bNumEmbMIDIJack         2
> > >           baAssocJackID( 0)       9
> > >           baAssocJackID( 1)      11
> > >       Endpoint Descriptor:
> > >         [...]
> > >         bEndpointAddress     0x81  EP 1 IN
> > >         [...]
> > >         MIDIStreaming Endpoint Descriptor:
> > >           bLength                 8
> > >           bDescriptorType        37
> > >           bDescriptorSubtype      1 (Invalid)
> > >           bNumEmbMIDIJack         4
> > >           baAssocJackID( 0)       2
> > >           baAssocJackID( 1)       4
> > >           baAssocJackID( 2)       6
> > >           baAssocJackID( 3)       8
> > > 
> > > Which lists all the jack IDs where they should be.
> > 
> > Hmm, I don't get your point.  The embedded IN is paired with the
> > external OUT.  That's the intended behavior, no?
> 
> Yes, all the endpoint assignments are correct - when they appear in the
> lists!
> 
> The issue is setting bNumEmbMIDIJack and bLength in the MIDIStreaming
> Endpoint Descriptors.  Without this patch these are set the wrong way
> round so either some ports do not appear or there are bogus entries
> containing uninitialized stack memory.

OK, now point taken.  The main problem here is the definition of
in_port and out_ports aren't really clear.  If in_ports really
corresponds to external IN jacks, then we may correct rather like:

--- a/drivers/usb/gadget/function/f_midi.c
+++ b/drivers/usb/gadget/function/f_midi.c
@@ -968,7 +968,7 @@ static int f_midi_bind(struct usb_configuration *c, struct usb_function *f)
 		midi_function[i++] = (struct usb_descriptor_header *) out_emb;
 
 		/* link it to the endpoint */
-		ms_in_desc.baAssocJackID[n] = out_emb->bJackID;
+		ms_out_desc.baAssocJackID[n] = out_emb->bJackID;
 	}
 
 	/* configure the external OUT jacks, each linked to an embedded IN jack */
@@ -996,7 +996,7 @@ static int f_midi_bind(struct usb_configuration *c, struct usb_function *f)
 		midi_function[i++] = (struct usb_descriptor_header *) out_ext;
 
 		/* link it to the endpoint */
-		ms_out_desc.baAssocJackID[n] = in_emb->bJackID;
+		ms_in_desc.baAssocJackID[n] = in_emb->bJackID;
 	}
 
 	/* configure the endpoint descriptors ... */

OTOH, the current code will make the actual appearance other way
round, likely more confusing.  So I believe your fix makes sense.

But it'd be helpful to extend the description a bit more to clarify
this confusion.  I guess this confusion came from the association
between the embedded and external jacks, and the patch corrects it.


thanks,

Takashi

> 
> 
> 
> Regards,
> John
> 
> > > > > Cc: stable@vger.kernel.org
> > > > > Fixes: c8933c3f79568 ("USB: gadget: f_midi: allow a dynamic number of input and output ports")
> > > > > Signed-off-by: John Keeping <jkeeping@inmusicbrands.com>
> > > > > ---
> > > > >  drivers/usb/gadget/function/f_midi.c | 8 ++++----
> > > > >  1 file changed, 4 insertions(+), 4 deletions(-)
> > > > > 
> > > > > diff --git a/drivers/usb/gadget/function/f_midi.c b/drivers/usb/gadget/function/f_midi.c
> > > > > index 837fcdfa3840f..6cc3d86cb4774 100644
> > > > > --- a/drivers/usb/gadget/function/f_midi.c
> > > > > +++ b/drivers/usb/gadget/function/f_midi.c
> > > > > @@ -1000,11 +1000,11 @@ 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;
> > > > > -- 
> > > > > 2.48.1
> > > > > 
> > > > > 

^ permalink raw reply	[flat|nested] 7+ messages in thread

* Re: [PATCH] usb: gadget: f_midi: fix MIDI Streaming descriptor lengths
  2025-01-30 12:17         ` Takashi Iwai
@ 2025-01-30 17:10           ` John Keeping
  0 siblings, 0 replies; 7+ messages in thread
From: John Keeping @ 2025-01-30 17:10 UTC (permalink / raw)
  To: Takashi Iwai
  Cc: linux-usb, stable, Greg Kroah-Hartman, Kees Cook, Abdul Rahim,
	Michael Grzeschik, Jeff Johnson, Felipe Balbi, Daniel Mack,
	linux-kernel

On Thu, Jan 30, 2025 at 01:17:59PM +0100, Takashi Iwai wrote:
> On Thu, 30 Jan 2025 11:59:05 +0100,
> John Keeping wrote:
> > 
> > On Thu, Jan 30, 2025 at 11:50:07AM +0100, Takashi Iwai wrote:
> > > On Wed, 29 Jan 2025 18:31:35 +0100,
> > > John Keeping wrote:
> > > > 
> > > > On Wed, Jan 29, 2025 at 05:40:04PM +0100, Takashi Iwai wrote:
> > > > > On Wed, 29 Jan 2025 17:05:19 +0100,
> > > > > John Keeping wrote:
> > > > > > 
> > > > > > In the two loops before setting the MIDIStreaming descriptors,
> > > > > > ms_in_desc.baAssocJackID[] has entries written for "in_ports" values and
> > > > > > ms_out_desc.baAssocJackID[] has entries written for "out_ports" values.
> > > > > > But the counts and lengths are set the other way round in the
> > > > > > descriptors.
> > > > > > 
> > > > > > Fix the descriptors so that the bNumEmbMIDIJack values and the
> > > > > > descriptor lengths match the number of entries populated in the trailing
> > > > > > arrays.
> > > > > 
> > > > > Are you sure that it's a correct change?
> > > > > 
> > > > > IIUC, the in_ports and out_ports parameters are for external IN and
> > > > > OUT jacks, where an external OUT jack is connected to an embedded IN
> > > > > jack, and an external IN jack is connected to an embedded OUT jack.
> > > > 
> > > > I think it depends how the in_ports and out_ports values in configfs are
> > > > interpreted.  However, the case where in_ports != out_ports has been
> > > > broken since these files were added!
> > > > 
> > > > Without this change, setting in_ports=4 out_ports=2 we end up with:
> > > > 
> > > >       Endpoint Descriptor:
> > > >         [...]
> > > >         bEndpointAddress     0x01  EP 1 OUT
> > > >         [...]
> > > >         MIDIStreaming Endpoint Descriptor:
> > > >           bLength                 8
> > > >           bDescriptorType        37
> > > >           bDescriptorSubtype      1 (Invalid)
> > > >           bNumEmbMIDIJack         4
> > > >           baAssocJackID( 0)       9
> > > >           baAssocJackID( 1)      11
> > > >           baAssocJackID( 2)       9
> > > >           baAssocJackID( 3)       0
> > > >       Endpoint Descriptor:
> > > >         [...]
> > > >         bEndpointAddress     0x81  EP 1 IN
> > > >         [...]
> > > >         MIDIStreaming Endpoint Descriptor:
> > > >           bLength                 6
> > > >           bDescriptorType        37
> > > >           bDescriptorSubtype      1 (Invalid)
> > > >           bNumEmbMIDIJack         2
> > > >           baAssocJackID( 0)       2
> > > >           baAssocJackID( 1)       4
> > > > 
> > > > Note that baAssocJackID values 2 and 3 on the OUT endpoint are wrong.
> > > > 
> > > > From the same config, the jack definitions are:
> > > > 
> > > > 	1:  IN  External
> > > > 	2:  OUT Embedded, source 1
> > > > 	3:  IN  External
> > > > 	4:  OUT Embedded, source 3
> > > > 	5:  IN  External
> > > > 	6:  OUT Embedded, source 5
> > > > 	7:  IN  External
> > > > 	8:  OUT Embedded, source 7
> > > > 
> > > > 	9:  IN  Embedded
> > > > 	10: OUT External, source 9
> > > > 	11: IN  Embedded
> > > > 	12: OUT External, source 11
> > > > 
> > > > So it seems that the first 2 entries in each endpoint list are correct.
> > > > For the OUT endpoint, jacks 9 and 11 are embedded IN jacks and for the
> > > > IN endpoint, jacks 2 and 4 are embedded OUT jacks.
> > > > 
> > > > The problem is that the OUT endpoint lists two extra invalid jack IDs
> > > > and the IN endpoint should list jacks 6 and 8 but does not.
> > > > 
> > > > After applying this patch, the endpoint descriptors for the same config
> > > > are:
> > > > 
> > > >       Endpoint Descriptor:
> > > >         [...]
> > > >         bEndpointAddress     0x01  EP 1 OUT
> > > >         [...]
> > > >         MIDIStreaming Endpoint Descriptor:
> > > >           bLength                 6
> > > >           bDescriptorType        37
> > > >           bDescriptorSubtype      1 (Invalid)
> > > >           bNumEmbMIDIJack         2
> > > >           baAssocJackID( 0)       9
> > > >           baAssocJackID( 1)      11
> > > >       Endpoint Descriptor:
> > > >         [...]
> > > >         bEndpointAddress     0x81  EP 1 IN
> > > >         [...]
> > > >         MIDIStreaming Endpoint Descriptor:
> > > >           bLength                 8
> > > >           bDescriptorType        37
> > > >           bDescriptorSubtype      1 (Invalid)
> > > >           bNumEmbMIDIJack         4
> > > >           baAssocJackID( 0)       2
> > > >           baAssocJackID( 1)       4
> > > >           baAssocJackID( 2)       6
> > > >           baAssocJackID( 3)       8
> > > > 
> > > > Which lists all the jack IDs where they should be.
> > > 
> > > Hmm, I don't get your point.  The embedded IN is paired with the
> > > external OUT.  That's the intended behavior, no?
> > 
> > Yes, all the endpoint assignments are correct - when they appear in the
> > lists!
> > 
> > The issue is setting bNumEmbMIDIJack and bLength in the MIDIStreaming
> > Endpoint Descriptors.  Without this patch these are set the wrong way
> > round so either some ports do not appear or there are bogus entries
> > containing uninitialized stack memory.
> 
> OK, now point taken.  The main problem here is the definition of
> in_port and out_ports aren't really clear.  If in_ports really
> corresponds to external IN jacks, then we may correct rather like:
> 
> --- a/drivers/usb/gadget/function/f_midi.c
> +++ b/drivers/usb/gadget/function/f_midi.c
> @@ -968,7 +968,7 @@ static int f_midi_bind(struct usb_configuration *c, struct usb_function *f)
>  		midi_function[i++] = (struct usb_descriptor_header *) out_emb;
>  
>  		/* link it to the endpoint */
> -		ms_in_desc.baAssocJackID[n] = out_emb->bJackID;
> +		ms_out_desc.baAssocJackID[n] = out_emb->bJackID;
>  	}
>  
>  	/* configure the external OUT jacks, each linked to an embedded IN jack */
> @@ -996,7 +996,7 @@ static int f_midi_bind(struct usb_configuration *c, struct usb_function *f)
>  		midi_function[i++] = (struct usb_descriptor_header *) out_ext;
>  
>  		/* link it to the endpoint */
> -		ms_out_desc.baAssocJackID[n] = in_emb->bJackID;
> +		ms_in_desc.baAssocJackID[n] = in_emb->bJackID;
>  	}
>  
>  	/* configure the endpoint descriptors ... */
> 
> OTOH, the current code will make the actual appearance other way
> round, likely more confusing.  So I believe your fix makes sense.

It always takes me a few minutes to get used to working in device-side
USB because IN and OUT refer to the host's view.

But I think "in_ports" and "out_ports" here are consistent with that.
"in_ports" are the ports that send MIDI into the USB host, and
"out_ports" are the ports receiving MIDI from the USB host over an OUT
endpoint.

> But it'd be helpful to extend the description a bit more to clarify
> this confusion.  I guess this confusion came from the association
> between the embedded and external jacks, and the patch corrects it.

I'll rewrite the commit message to include some more of this context and
send a v2 later today or tomorrow.


Regards,
John

> > > > > > Cc: stable@vger.kernel.org
> > > > > > Fixes: c8933c3f79568 ("USB: gadget: f_midi: allow a dynamic number of input and output ports")
> > > > > > Signed-off-by: John Keeping <jkeeping@inmusicbrands.com>
> > > > > > ---
> > > > > >  drivers/usb/gadget/function/f_midi.c | 8 ++++----
> > > > > >  1 file changed, 4 insertions(+), 4 deletions(-)
> > > > > > 
> > > > > > diff --git a/drivers/usb/gadget/function/f_midi.c b/drivers/usb/gadget/function/f_midi.c
> > > > > > index 837fcdfa3840f..6cc3d86cb4774 100644
> > > > > > --- a/drivers/usb/gadget/function/f_midi.c
> > > > > > +++ b/drivers/usb/gadget/function/f_midi.c
> > > > > > @@ -1000,11 +1000,11 @@ 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;
> > > > > > -- 
> > > > > > 2.48.1
> > > > > > 
> > > > > > 

^ permalink raw reply	[flat|nested] 7+ messages in thread

end of thread, other threads:[~2025-01-30 17:10 UTC | newest]

Thread overview: 7+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2025-01-29 16:05 [PATCH] usb: gadget: f_midi: fix MIDI Streaming descriptor lengths John Keeping
2025-01-29 16:40 ` Takashi Iwai
2025-01-29 17:31   ` John Keeping
2025-01-30 10:50     ` Takashi Iwai
2025-01-30 10:59       ` John Keeping
2025-01-30 12:17         ` Takashi Iwai
2025-01-30 17:10           ` John Keeping

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