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From: "Dave Korn" <dave DOT korn AT artimi DOT com>
To: <cygwin AT cygwin DOT com>
Subject: RE: autossh crash with 20050314 and earlier cygwin1.dll
Date: Wed, 16 Mar 2005 18:06:20 -0000
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X-OriginalArrivalTime: 16 Mar 2005 18:06:35.0291 (UTC) FILETIME=[E41FEEB0:01C52A52]

----Original Message----
>From: Andrew Schulman
>Sent: 16 March 2005 17:08


> Would the job be easier in my case, where I have a repeatable crash?  I
> provided strace output in the earlier thread about my autossh problems,
> but haven't tried using any debug builds of cygwin1.dll.  I'm not
> conversant with debuggers, but I have used gdb before and could work my
> way through it.  Let me know if this would be useful, and how best to go
> about it.


  Thanks, it's good of you to offer, but as you may have seen, cgf's already
put his finger on it: the code in autossh calls free (...) on a pointer that
it didn't get from one of the *alloc (...)-family functions.  That's the
problem (undefined behaviour) and his fix is the correct solution.

  GOK why it works on glibc-based systems, but I guess it must, or the
problem would surely have cropped up before.  Hmmmmm......

dk AT mace /gnu/glibc-2.3.4/resolv> cat -n gethnamaddr.c
 [........snip!........]
   103
   104  static struct hostent host;
   105  static char *host_aliases[MAXALIASES];
   106  static char hostbuf[8*1024];
 [........snip!........]

  Well, it also uses a static buffer.  Guess glibc free (...) must be more
robust in the presence of garbage input than newlib free (...), although
that's odd, since they're both based on dl-malloc under the hood.


    cheers,
      DaveK
-- 
Can't think of a witty .sigline today....


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