Re: ftdi_sio BUG: NULL pointer dereference

[Mike Remski]

On 06/02/2014 01:46 PM, Johan Hovold wrote:
> On Mon, Jun 02, 2014 at 01:11:37PM -0400, Mike Remski wrote:
> > On 06/02/2014 12:49 PM, Johan Hovold wrote:
> > > On Mon, Jun 02, 2014 at 12:24:44PM -0400, Mike Remski wrote:
> > > > On 06/02/2014 12:20 PM, Johan Hovold wrote:
> > > > > On Mon, Jun 02, 2014 at 12:02:40PM -0400, Mike Remski wrote:
> > > > > > On 06/02/2014 11:40 AM, Johan Hovold wrote:
> > > > > > > [ Please avoid top-posting. ]
> > > > > > >
> > > > > > > On Mon, Jun 02, 2014 at 11:16:11AM -0400, Mike Remski wrote:
> > > > > The third interface lacks endpoints and crashes the ftdi_sio driver.
> > > > > This shouldn't happen (even if you're forcing the wrong driver to bind),
> > > > > so I'll fix it up if still broken in v3.15-rc.
> > > > Johan,
> > > > Thanks again.  Yes, the device does indeed have an FTDI embedded in it;
> > > > they've programmed in their own ids.  They supply a Windows driver for
> > > > it, but that doesn't do me any good.  :)
> > > Not just their own ID's it seems.
> > >
> > > Have you tried just using the cdc-acm driver? The ports should up as
> > > /dev/ttyACMx instead of ttyUSBx.
> > Not yet, next on the list.
> You really should try this before anything else. :)
>
> > I'm suspecting that bNumEndpoints == 0 is causing endpoint[1].desc to
> > stay at NULL (line 1567 in 3.1.4.5 source), so by the time it gets used
> > later on, I'm hitting the NULL dereference.
> Yeah, the code is obviously broken (also in v3.15-rc). It should
> probably work to just return from ftdi_set_max_packet_size if
> num_endpoints is 0 if you want to try that (or you can use your ?:
> construct), but I should be able to fix this up properly on Wednesday.
>
> Thanks,
> Johan
Johan,
I had a chance to play around with code over in ftdi_sio.c;   adding this:

        if (!num_endpoints) {
                return;
        }
 after the "Number of endpoints" message gets rid of the crash, 
everything looks to be working correctly.

Thanks again

m

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