Re: usb-serial.c question - potential Memory fault

On Mon, Jul 30, 2007 at 06:04:06PM +0200, [email protected] wrote:
> Greg,
> 
> It is a problem because I use the pre-allocated buffer given by the layer
> usb-serial.  Of course, I can create a new urb structure with a bigger
> buffer but I just suggest that using the buffer stored in the
> usb_serial_device seems to be logic and like a said, other driver use
> it without checking the buffer_size. Are you sure that the pl2303 is
> well protected against a buffer overflow ?

I do not see any paths within the pl2303 driver that would cause such a
buffer overflow at all.

> What happens if a pl2303 device give a maxsize of 64 bytes like my device ?

It should "just work", as it looks at the size of the buffer it is
filling up when it does it (look at the logic in pl2303_send() for
confirmation of this.)

The 2.4 version of the pl2303 driver is much different, I don't remember
which one you copied your driver from, but I think that one also should
be just fine.

> The driver will then make a buffer overflow and a kernel panic may
> occur. This was the module I used to study and write my own driver.

If you see the same error for the pl2303 driver, please let me know.

> So I agree with the proposition of Oliver to add a buffer_size in the
> usb_serial_driver structure.
> This is very useful to prepare a buffer able to make bulk transfer.

I don't think it is necessary to add as it has not been a problem yet
for any driver that I know of.

I think you are just doing something wrong in your driver :)

thanks,

greg k-h

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