[sane-devel] Problem with libusb and 64 bits 2.6.25 kernel

[Nicolas]

Sounds good then. Thank Denis for your feedback!

Nicolas

Le mercredi 25 juin 2008 à 23:25 -0700, Dennis Lou a écrit :
> FYI, I managed to scrape together a spare machine for testing and the patch works fine here.
> 
> -Dennis
> 
> ----- Original Message ----
> From: Sam Varshavchik <mrsam at courier-mta.com>
> To: Dennis Lou <dlou99 at yahoo.com>
> Cc: Nicolas <nicolas.martin at freesurf.fr>; mrsam-guest <mrsam-guest at alioth.debian.org>; sane-devel <sane-devel at lists.alioth.debian.org>
> Sent: Wednesday, June 25, 2008 3:20:22 PM
> Subject: Re: [sane-devel] Problem with libusb and 64 bits 2.6.25 kernel
> 
> Dennis Lou writes:
> 
> > The way I see it, Sam's buffer overflow concern is predicated on a
> > misbehaving device.  I haven't witnessed it but it is possible given that
> > we're reverse engineering things rather than working from a formal spec. 
> > Nicolas' buffer overflow concern is predicated on a misbehaving usb stack.
> >  It's also possible, but probably less likely than Sam's concern.  Which
> > to implement depends on how paranoid you are about the behavior of the
> > device and libusb.
> 
> Clarification: my patch is needed to fix the following bug, referenced 
> earlier in the thread:
> 
> >>> Hi Dennis, 
> >>> 
> >>> A bug was opened a while back by Sam Varshavchik, concerning the pixma
> >>> backend for Canon ImageClass MF-4270, when compiled and used on a 64
> >>> bits platform (no issue so far on 32 bits), details are given here:
> >>> 
> >>> https://alioth.debian.org/tracker/?group_id=30186&atid=410366&func=detail&aid=310861
> 
> The original code issues a read request to libusb for more bytes than 
> actually expected, and, apparently, on some hardware that causes a USB 
> timeout, with Various Bad Things™, as I described in the bug. Besides a 
> single scan now taking ~30 minutes, the resulting pnm is corrupted.
> 
> By changing the code not to ask to read more than what's expected, that 
> fixes both the original bug, and the overflow problem.
> 
> 
>