usb: gadget: Don't attempt to dequeue requests for a disabled USB endpoint on Freescale hardware

Some gadget drivers may attempt to dequeue requests for an endpoint that has
already been disabled. For example, in the UVC gadget driver, uvc_function_set_alt()
will call usb_ep_disable() when alt setting 0 is selected. When the userspace
application subsequently issues the VIDIOC_STREAMOFF ioctl, uvc_video_enable()
invokes usb_ep_dequeue() to ensure that all requests have been cancelled.

For the Freescale High Speed Dual-Role USB controller, fsl_ep_dequeue() provides
the implementation of usb_ep_dequeue(). If this is called for a disabled endpoint,
a kernel oops will occur when the ep->ep.desc field is dereferenced (by ep_index()).
fsl_ep_disable() sets this field to NULL, as well as deleting all pending requests
for the endpoint.

This patch adds an additional check to fsl_ep_dequeue() to ensure that the
endpoint has not already been disabled before attempting to dequeue requests.

Signed-off-by: Simon Haggett <redacted>
---
 drivers/usb/gadget/fsl_udc_core.c |    5 ++++-
 1 files changed, 4 insertions(+), 1 deletions(-)

diff --git a/drivers/usb/gadget/fsl_udc_core.c b/drivers/usb/gadget/fsl_udc_core.c
index 6ae70cb..acd513b 100644
--- a/drivers/usb/gadget/fsl_udc_core.c
+++ b/drivers/usb/gadget/fsl_udc_core.c

@@ -955,7 +955,10 @@ static int fsl_ep_dequeue(struct usb_ep *_ep, struct usb_request *_req)
 	int ep_num, stopped, ret = 0;
 	u32 epctrl;
 
-	if (!_ep || !_req)
+	/* Ensure that the ep and request are valid, and the ep is not
+	 * disabled
+	 */
+	if (!_ep || !_req || !ep->ep.desc)
 		return -EINVAL;
 
 	spin_lock_irqsave(&ep->udc->lock, flags);

-- 
1.7.4.1

Hi,

On Fri, Oct 19, 2012 at 06:19:26PM +0100, Simon Haggett wrote:

Some gadget drivers may attempt to dequeue requests for an endpoint that has
already been disabled. For example, in the UVC gadget driver, uvc_function_set_alt()
will call usb_ep_disable() when alt setting 0 is selected. When the userspace
application subsequently issues the VIDIOC_STREAMOFF ioctl, uvc_video_enable()
invokes usb_ep_dequeue() to ensure that all requests have been cancelled.

bug is on uvc gadget, then. Laurent ?

Also, fsl should be removed from the tree, I'm trying to persuade iMX
folks to use drivers/usb/chipidea instead.

-- 
balbi

-----Original Message-----
From: Felipe Balbi [mailto:<redacted>]
Sent: Saturday, October 20, 2012 1:37 AM
To: Simon Haggett
Cc: Li Yang-R58472; Felipe Balbi; Greg Kroah-Hartman; linux-
usb@vger.kernel.org; linuxppc-dev@lists.ozlabs.org; linux-
kernel@vger.kernel.org; Laurent Pinchart
Subject: Re: [PATCH 1/1] usb: gadget: Don't attempt to dequeue requests
for a disabled USB endpoint on Freescale hardware
=20
Hi,
=20
On Fri, Oct 19, 2012 at 06:19:26PM +0100, Simon Haggett wrote:

quoted

Some gadget drivers may attempt to dequeue requests for an endpoint
that has already been disabled. For example, in the UVC gadget driver,
uvc_function_set_alt() will call usb_ep_disable() when alt setting 0
is selected. When the userspace application subsequently issues the
VIDIOC_STREAMOFF ioctl, uvc_video_enable() invokes usb_ep_dequeue() to

ensure that all requests have been cancelled.
=20
bug is on uvc gadget, then. Laurent ?
=20
Also, fsl should be removed from the tree, I'm trying to persuade iMX
folks to use drivers/usb/chipidea instead.

Besides the iMX usage, the driver is also being used by many Freescale Powe=
rPC/Coldfire SoCs.  I agree that it's ideal to move to a common driver.  Bu=
t it is a large task to make the chipidea driver works for all the hardware=
 that fsl_udc had supported and been tested on.

=20

quoted

For the Freescale High Speed Dual-Role USB controller,
fsl_ep_dequeue() provides the implementation of usb_ep_dequeue(). If
this is called for a disabled endpoint, a kernel oops will occur when

the ep->ep.desc field is dereferenced (by ep_index()).

quoted

fsl_ep_disable() sets this field to NULL, as well as deleting all
pending requests for the endpoint.

This patch adds an additional check to fsl_ep_dequeue() to ensure that
the endpoint has not already been disabled before attempting to dequeue

requests.

quoted

Signed-off-by: Simon Haggett <redacted>
---
 drivers/usb/gadget/fsl_udc_core.c |    5 ++++-
 1 files changed, 4 insertions(+), 1 deletions(-)

diff --git a/drivers/usb/gadget/fsl_udc_core.c

b/drivers/usb/gadget/fsl_udc_core.c
index 6ae70cb..acd513b 100644

--- a/drivers/usb/gadget/fsl_udc_core.c
+++ b/drivers/usb/gadget/fsl_udc_core.c

@@ -955,7 +955,10 @@ static int fsl_ep_dequeue(struct usb_ep *_ep,

struct usb_request *_req)

quoted

 	int ep_num, stopped, ret =3D 0;
 	u32 epctrl;

-	if (!_ep || !_req)
+	/* Ensure that the ep and request are valid, and the ep is not
+	 * disabled
+	 */
+	if (!_ep || !_req || !ep->ep.desc)
 		return -EINVAL;

 	spin_lock_irqsave(&ep->udc->lock, flags);
--
1.7.4.1

=20
--

1 more quoted lines

On Mon, Oct 22, 2012 at 03:33:19AM +0000, Li Yang-R58472 wrote:

quoted

-----Original Message-----
From: Felipe Balbi [mailto:<redacted>]
Sent: Saturday, October 20, 2012 1:37 AM
To: Simon Haggett
Cc: Li Yang-R58472; Felipe Balbi; Greg Kroah-Hartman; linux-
usb@vger.kernel.org; linuxppc-dev@lists.ozlabs.org; linux-
kernel@vger.kernel.org; Laurent Pinchart
Subject: Re: [PATCH 1/1] usb: gadget: Don't attempt to dequeue requests
for a disabled USB endpoint on Freescale hardware

Hi,

On Fri, Oct 19, 2012 at 06:19:26PM +0100, Simon Haggett wrote:

quoted

Some gadget drivers may attempt to dequeue requests for an endpoint
that has already been disabled. For example, in the UVC gadget driver,
uvc_function_set_alt() will call usb_ep_disable() when alt setting 0
is selected. When the userspace application subsequently issues the
VIDIOC_STREAMOFF ioctl, uvc_video_enable() invokes usb_ep_dequeue() to

ensure that all requests have been cancelled.

bug is on uvc gadget, then. Laurent ?

Also, fsl should be removed from the tree, I'm trying to persuade iMX
folks to use drivers/usb/chipidea instead.

Besides the iMX usage, the driver is also being used by many Freescale
PowerPC/Coldfire SoCs.  I agree that it's ideal to move to a common
driver.  But it is a large task to make the chipidea driver works for
all the hardware that fsl_udc had supported and been tested on.

I understand that, but we just can't keep so many duplicated drivers in
mainline. chipidea udc had at least 3 different implementations. Now
it's the time to combine all of those and stick to a single driver.

Just make a plan to slowly move towards chipidea in the upcoming few
merge windows. I can continue to take in bugfixes for fsl_udc, but only
if I see that you guys are working towards merging with chipidea driver.

-- 
balbi

Hi,

On Monday 22 October 2012 03:33:19 Li Yang-R58472 wrote:

On Saturday, October 20, 2012 1:37 AM Felipe Balbi wrote:

quoted

On Fri, Oct 19, 2012 at 06:19:26PM +0100, Simon Haggett wrote:

quoted

Some gadget drivers may attempt to dequeue requests for an endpoint
that has already been disabled. For example, in the UVC gadget driver,
uvc_function_set_alt() will call usb_ep_disable() when alt setting 0
is selected. When the userspace application subsequently issues the
VIDIOC_STREAMOFF ioctl, uvc_video_enable() invokes usb_ep_dequeue() to

ensure that all requests have been cancelled.

bug is on uvc gadget, then. Laurent ?

We've discussed this topic a couple of months before. I believe that's not a 
bug.

http://68.183.106.108/lists/linux-usb/msg68869.html

quoted

Also, fsl should be removed from the tree, I'm trying to persuade iMX
folks to use drivers/usb/chipidea instead.

Besides the iMX usage, the driver is also being used by many Freescale
PowerPC/Coldfire SoCs.  I agree that it's ideal to move to a common driver.
But it is a large task to make the chipidea driver works for all the
hardware that fsl_udc had supported and been tested on.

quoted

quoted

For the Freescale High Speed Dual-Role USB controller,
fsl_ep_dequeue() provides the implementation of usb_ep_dequeue(). If
this is called for a disabled endpoint, a kernel oops will occur when

the ep->ep.desc field is dereferenced (by ep_index()).

quoted

fsl_ep_disable() sets this field to NULL, as well as deleting all
pending requests for the endpoint.

This patch adds an additional check to fsl_ep_dequeue() to ensure that
the endpoint has not already been disabled before attempting to dequeue

requests.

quoted

Signed-off-by: Simon Haggett <redacted>
---

 drivers/usb/gadget/fsl_udc_core.c |    5 ++++-
 1 files changed, 4 insertions(+), 1 deletions(-)

diff --git a/drivers/usb/gadget/fsl_udc_core.c

b/drivers/usb/gadget/fsl_udc_core.c
index 6ae70cb..acd513b 100644

--- a/drivers/usb/gadget/fsl_udc_core.c
+++ b/drivers/usb/gadget/fsl_udc_core.c

@@ -955,7 +955,10 @@ static int fsl_ep_dequeue(struct usb_ep *_ep,

struct usb_request *_req)

quoted

 	int ep_num, stopped, ret = 0;
 	u32 epctrl;

-	if (!_ep || !_req)

5 more quoted lines

Shouldn't that last check be done with a lock taken ?

quoted

quoted

 	spin_lock_irqsave(&ep->udc->lock, flags);

-- 
Regards,

Laurent Pinchart

Hi,

On Mon, Oct 22, 2012 at 12:47:21PM +0200, Laurent Pinchart wrote:

Hi,

On Monday 22 October 2012 03:33:19 Li Yang-R58472 wrote:

quoted

On Saturday, October 20, 2012 1:37 AM Felipe Balbi wrote:

quoted

On Fri, Oct 19, 2012 at 06:19:26PM +0100, Simon Haggett wrote:

quoted

Some gadget drivers may attempt to dequeue requests for an endpoint
that has already been disabled. For example, in the UVC gadget driver,
uvc_function_set_alt() will call usb_ep_disable() when alt setting 0
is selected. When the userspace application subsequently issues the
VIDIOC_STREAMOFF ioctl, uvc_video_enable() invokes usb_ep_dequeue() to

ensure that all requests have been cancelled.

bug is on uvc gadget, then. Laurent ?

We've discussed this topic a couple of months before. I believe that's not a 
bug.

http://68.183.106.108/lists/linux-usb/msg68869.html

fair enough :-)

That's a different case, however. At the link above we're discussing
dequeueing a request which is already being dequeued. $SUBJECT is trying
to fix dequeueing of a request for an endpoint which isn't even enabled.

-- 
balbi

Hi

On 22/10/12 11:47, Laurent Pinchart wrote:

Hi,

On Monday 22 October 2012 03:33:19 Li Yang-R58472 wrote:

quoted

On Saturday, October 20, 2012 1:37 AM Felipe Balbi wrote:

quoted

On Fri, Oct 19, 2012 at 06:19:26PM +0100, Simon Haggett wrote:

quoted

Some gadget drivers may attempt to dequeue requests for an endpoint
that has already been disabled. For example, in the UVC gadget driver,
uvc_function_set_alt() will call usb_ep_disable() when alt setting 0
is selected. When the userspace application subsequently issues the
VIDIOC_STREAMOFF ioctl, uvc_video_enable() invokes usb_ep_dequeue() to

ensure that all requests have been cancelled.

bug is on uvc gadget, then. Laurent ?

We've discussed this topic a couple of months before. I believe that's not a
bug.

http://68.183.106.108/lists/linux-usb/msg68869.html

quoted

quoted

Also, fsl should be removed from the tree, I'm trying to persuade iMX
folks to use drivers/usb/chipidea instead.

Besides the iMX usage, the driver is also being used by many Freescale
PowerPC/Coldfire SoCs.  I agree that it's ideal to move to a common driver.
But it is a large task to make the chipidea driver works for all the
hardware that fsl_udc had supported and been tested on.

quoted

quoted

For the Freescale High Speed Dual-Role USB controller,
fsl_ep_dequeue() provides the implementation of usb_ep_dequeue(). If
this is called for a disabled endpoint, a kernel oops will occur when

the ep->ep.desc field is dereferenced (by ep_index()).

quoted

fsl_ep_disable() sets this field to NULL, as well as deleting all
pending requests for the endpoint.

This patch adds an additional check to fsl_ep_dequeue() to ensure that
the endpoint has not already been disabled before attempting to dequeue

27 more quoted lines

I had presumed a lock wasn't necessary because ep->ep.desc is only set to NULL by fsl_ep_disable() which, since it is called by usb_ep_disable(), should only be invoked when no other task is using the endpoint (according to include/linux/usb/gadget.h). Furthermore, the chipidea UDC driver does check the equivalent of this field is not NULL without taking a lock (ep_dequeue() in drivers/usb/chipidea/udc.c).

However, it is possible that I'm misunderstanding something here, so apologies if I am.

quoted

quoted

quoted

  	spin_lock_irqsave(&ep->udc->lock, flags);

Many thanks

Simon

Hi Simon,

On Monday 22 October 2012 12:49:51 Simon Haggett wrote:

On 22/10/12 11:47, Laurent Pinchart wrote:

quoted

On Monday 22 October 2012 03:33:19 Li Yang-R58472 wrote:

quoted

On Saturday, October 20, 2012 1:37 AM Felipe Balbi wrote:

quoted

On Fri, Oct 19, 2012 at 06:19:26PM +0100, Simon Haggett wrote:

quoted

Some gadget drivers may attempt to dequeue requests for an endpoint
that has already been disabled. For example, in the UVC gadget driver,
uvc_function_set_alt() will call usb_ep_disable() when alt setting 0
is selected. When the userspace application subsequently issues the
VIDIOC_STREAMOFF ioctl, uvc_video_enable() invokes usb_ep_dequeue() to

ensure that all requests have been cancelled.

bug is on uvc gadget, then. Laurent ?

We've discussed this topic a couple of months before. I believe that's not
a bug.

http://68.183.106.108/lists/linux-usb/msg68869.html

quoted

quoted

Also, fsl should be removed from the tree, I'm trying to persuade iMX
folks to use drivers/usb/chipidea instead.

Besides the iMX usage, the driver is also being used by many Freescale
PowerPC/Coldfire SoCs.  I agree that it's ideal to move to a common
driver.
But it is a large task to make the chipidea driver works for all the
hardware that fsl_udc had supported and been tested on.

quoted

quoted

For the Freescale High Speed Dual-Role USB controller,
fsl_ep_dequeue() provides the implementation of usb_ep_dequeue(). If
this is called for a disabled endpoint, a kernel oops will occur when

the ep->ep.desc field is dereferenced (by ep_index()).

quoted

fsl_ep_disable() sets this field to NULL, as well as deleting all
pending requests for the endpoint.

This patch adds an additional check to fsl_ep_dequeue() to ensure that
the endpoint has not already been disabled before attempting to dequeue

39 more quoted lines

I might be wrong as well :-) I just wanted to point out something that 
appeared to me as a possible issue.

quoted

quoted

quoted

quoted

  	spin_lock_irqsave(&ep->udc->lock, flags);

-- 
Regards,

Laurent Pinchart

Hi Felipe,

On Monday 22 October 2012 13:56:01 Felipe Balbi wrote:

On Mon, Oct 22, 2012 at 12:47:21PM +0200, Laurent Pinchart wrote:

quoted

On Monday 22 October 2012 03:33:19 Li Yang-R58472 wrote:

quoted

On Saturday, October 20, 2012 1:37 AM Felipe Balbi wrote:

quoted

On Fri, Oct 19, 2012 at 06:19:26PM +0100, Simon Haggett wrote:

quoted

Some gadget drivers may attempt to dequeue requests for an endpoint
that has already been disabled. For example, in the UVC gadget
driver, uvc_function_set_alt() will call usb_ep_disable() when alt
setting 0 is selected. When the userspace application subsequently
issues the VIDIOC_STREAMOFF ioctl, uvc_video_enable() invokes
usb_ep_dequeue() to ensure that all requests have been cancelled.

bug is on uvc gadget, then. Laurent ?

We've discussed this topic a couple of months before. I believe that's not
a bug.

http://68.183.106.108/lists/linux-usb/msg68869.html

fair enough :-)

That's a different case, however. At the link above we're discussing
dequeueing a request which is already being dequeued. $SUBJECT is trying
to fix dequeueing of a request for an endpoint which isn't even enabled.

You've got a point there :-) That's a different case indeed, I'm open to (at 
least evaluating) a fix in the UVC gadget driver if you think that's better.

-- 
Regards,

Laurent Pinchart

Hi,

On Thu, Oct 25, 2012 at 02:36:24AM +0200, Laurent Pinchart wrote:

Hi Felipe,

On Monday 22 October 2012 13:56:01 Felipe Balbi wrote:

quoted

On Mon, Oct 22, 2012 at 12:47:21PM +0200, Laurent Pinchart wrote:

quoted

On Monday 22 October 2012 03:33:19 Li Yang-R58472 wrote:

quoted

On Saturday, October 20, 2012 1:37 AM Felipe Balbi wrote:

quoted

On Fri, Oct 19, 2012 at 06:19:26PM +0100, Simon Haggett wrote:

quoted

Some gadget drivers may attempt to dequeue requests for an endpoint
that has already been disabled. For example, in the UVC gadget
driver, uvc_function_set_alt() will call usb_ep_disable() when alt
setting 0 is selected. When the userspace application subsequently
issues the VIDIOC_STREAMOFF ioctl, uvc_video_enable() invokes
usb_ep_dequeue() to ensure that all requests have been cancelled.

bug is on uvc gadget, then. Laurent ?

We've discussed this topic a couple of months before. I believe that's not
a bug.

http://68.183.106.108/lists/linux-usb/msg68869.html

fair enough :-)

That's a different case, however. At the link above we're discussing
dequeueing a request which is already being dequeued. $SUBJECT is trying
to fix dequeueing of a request for an endpoint which isn't even enabled.

You've got a point there :-) That's a different case indeed, I'm open to (at 
least evaluating) a fix in the UVC gadget driver if you think that's better.

I _do_ think that's better. If the endpoint isn't even enabled, why are
you trying to dequeue a request ? :-)

cheers

-- 
balbi