Re: [Tclhttpd-users] MS virus bogus URLs

[Brent W. <we...@pa...>]

I can't help but point out that you need to write a string that
consumes all of the processes virtual memory space in the heap,
which makes it very unlikely that the process will do anything but
get aborted by the operating sytsem.  Tcl will simply panic when its
malloc fails.
This is quite different than the standard gets() buffer overlow
attack where you can craftily put nasty code instructions on the stack
and cause the program to is misbehave in predictable ways.

>>>Colin McCormack said:
 > On Tue, 2004-07-20 at 14:51, Gerald W. Lester wrote:
 > > Colin McCormack wrote:
 > 
 > > >However, on a peripherally related matter, GPS has pointed out on tcl
 > > >chat that it's possible to crash the underlying tcl by sending an
 > > >*extremely* long string - because [gets] has no bounds checking on the
 > > >length of a line, and tcl will eventually run out of allocatable 
storage
 > > >for buffering.
 > 
 > > >Probably the best/only/complete solution to that is a TIP to 
fconfigure
 > > >a line limit.
 > 
 > > Actually I'd to see things use read and TIP for an option -breakon 
 > > ListOfChars
 > 
 > Why would you prefer this, Gerald?  I have no objection to it at all,
 > but I'm interested to know what it buys.
 > 
 > I think the gets overflow problem is similar to the C gets() overflow,
 > but it has the desirable property of crashing tcl rather than allowing
 > the sender to execute arbitrary code :)  Given that [gets] will continue
 > to exist, [gets] overflow and tcl crash will always be a problem, so I
 > see your suggestion as orthogonal to this specific problem, although it
 > may stand on its own merits.
 > -- 
 > Colin McCormack <co...@ch...>
 > 
 > 
 > 
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--
Brent Welch
Software Architect, Panasas Inc
Delivering the premier storage system for scalable Linux clusters

www.panasas.com
we...@pa...