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Re: [Discuss-gnuradio] uspr2 working intermittently/segmentation fault

From: Marcus D. Leech
Subject: Re: [Discuss-gnuradio] uspr2 working intermittently/segmentation fault
Date: Wed, 01 Apr 2009 19:28:22 -0400
User-agent: Thunderbird (X11/20090105)

Jeff Brower wrote:
> Not everything the FPGA does -- register format/contents, FIFO widths, etc -- 
> can be
> error checked.  There has to be some reasonable expectation on the software 
> side. 
> The typical method is a "revision id" register, the software checks this and 
> adjusts
> capabilities.  If the revision is too far behind or doesn't match expectation 
> then
> the software gives an error message.
> -Jeff
An error in the (expected) format of an external input should never
result in a Seg Fault.  Nothing wrong with doing
  "Gee, this parameter seems rather odd, I'm leaving".

Two decades of writing network protocol implementations has taught me
that  making dangerous assumptions about external
  inputs leads to  various  not-nice things happening, and notorious in
the press in the context of network protocols, those
  assumptions often lead to ugly security problems (note the SNMPV3
parser issues of a few years ago!).  No security issues
  here, to be sure, but being insufficiently paranoid about external
inputs of *any* kind has leads to spectacular downfall...

Provoking a Segmentation Fault is just impolite, if nothing else.

Marcus Leech
Principal Investigator, Shirleys Bay Radio Astronomy Consortium

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