Bug in USB Generic Serial driver

Bug in USB Generic Serial driver

[Greg KH]

Hi all,

It seems that the last round of hotplug changes broke a few more things.
If you load (or compile in) the USB Generic Serial driver, it will
_always_ grab any device that it is offered, if the user does not
specify a product and vendor id for it on the 'insmod' command line.

This is because its vendor and product id are set to 0 initially, with
_no_ match_flags setting either.  In the function, usb_match_id, a value
of 0 means accept any as a wild card.

So to fix this, either the Generic Serial driver can change its default
values to something like 0xffff for both the vendor and product id, or
we can change the usb_match_id function somehow, or something else?

I thought that the usb scanner driver would also have this problem, but
it looks like the ability to specify the vendor and product ids as a
module load parameter have been removed.

And I also don't like the ordering specificness of the new USB_DEVICE
macro, and liked the named initializers better, but can't think of a
better way to do it right this second.

Comments?

Thanks Randy, for pointing this problem out to me.

greg k-h


-- 
greg@(kroah|wirex).com

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Re: Bug in USB Generic Serial driver

[Adam J. Richter]

>From: Greg KH <greg@kroah.com>

[...]
>If you load (or compile in) the USB Generic Serial driver, it will
>_always_ grab any device that it is offered, if the user does not
>specify a product and vendor id for it on the 'insmod' command line.

>This is because its vendor and product id are set to 0 initially, with
>_no_ match_flags setting either.  In the function, usb_match_id, a value
>of 0 means accept any as a wild card.

	I have not tried this, but you should be able fix this problem
by changing the declaration of generic_device_ids to something like this:

static struct usb_device_id generic_device_ids[] = {
	{ match_flags: USB_DEVICE_ID_MATCH_VENDOR | USB_DEVICE_ID_MATCH_PRODUCT},
	{ } /* Terminating entry */
};

	This will cause the device and vendor ID's always to be tested.
From /usr/share/usb.ids, it looks like vendor ID 0 is reserved, so it
will not match unless the user sets it.

	I sympathize with your misgivings about the USB device ID
helper macros.  As I said a couple of days ago, if we shrink the
USB_DEVICE_ID_MATCH_xxxx names to USB_MATCH_xxxx, we should not need
so many helper macros to keep the code readable, and we should be able
to have labelled initializers.

Adam J. Richter     __     ______________   4880 Stevens Creek Blvd, Suite 104
adam@yggdrasil.com     \ /                  San Jose, California 95129-1034
+1 408 261-6630         | g g d r a s i l   United States of America
fax +1 408 261-6631      "Free Software For The Rest Of Us."

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RE: Bug in USB Generic Serial driver

[Dunlap, Randy]

> From: Greg KH [mailto:greg@kroah.com]
> 
> Hi all,
> 
> It seems that the last round of hotplug changes broke a few 
> more things.
> If you load (or compile in) the USB Generic Serial driver, it will
> _always_ grab any device that it is offered, if the user does not
> specify a product and vendor id for it on the 'insmod' command line.
> 
...
> 
> I thought that the usb scanner driver would also have this 
> problem, but
> it looks like the ability to specify the vendor and product ids as a
> module load parameter have been removed.

No, it's still there, partly in scanner.h, so it may also
have this problem.  I haven't tried it.

> And I also don't like the ordering specificness of the new USB_DEVICE
> macro, and liked the named initializers better, but can't think of a
> better way to do it right this second.
> 
> Comments?
> 
> Thanks Randy, for pointing this problem out to me.

I'm glad that you found the cause so quickly.

~Randy


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Re: Bug in USB Generic Serial driver

[Matthew Dharm]

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On Tue, Jan 09, 2001 at 12:09:12AM -0800, Adam J. Richter wrote:
> 	I sympathize with your misgivings about the USB device ID
> helper macros.  As I said a couple of days ago, if we shrink the
> USB_DEVICE_ID_MATCH_xxxx names to USB_MATCH_xxxx, we should not need
> so many helper macros to keep the code readable, and we should be able
> to have labelled initializers.

This is another case of "you can't please everyone".

Linus specifically objected to shorter macros and a lack of helper macros.
Go figure.  But, I wanted it in, and so I did it his way.  I didn't really
expect him to cram it into 2.4.0 final like he did... but hey, Linux is his
baby, not mine.

Matt

-- 
Matthew Dharm                              Home: mdharm-usb@one-eyed-alien.net 
Maintainer, Linux USB Mass Storage Driver

Your lips are twitching.  You're playing Quake aren't you.
					-- Stef to Greg
User Friendly, 8/11/1998

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