[sane-devel] Problem with libusb and 64 bits 2.6.25 kernel
mrsam at courier-mta.com
Wed Jun 25 22:20:22 UTC 2008
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:
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.
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