[Bug 810739] Re: strcpy output incorrect if src and dst overlap

[Distro-jumper]

Any news on this?? I can confirm the behavior on precise as well,
version 2.15-0ubuntu10.3.

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https://bugs.launchpad.net/bugs/810739

Title:
  strcpy output incorrect if src and dst overlap

Status in “eglibc” package in Ubuntu:
  Invalid

Bug description:
  A commercial application (Cadence) that runs with an older libc gives
  incorrect results with the current libc.  I've tracked down the
  problem to strcpy. If I make my own strcopy, following the template of
  https://bugzilla.redhat.com/show_bug.cgi?id=638477#c38, the tool gives
  correct results.  Here is mystrcpy.c:

  $ cat mystrcpy.c

  char *strcpy(char *dest, const char *src){
    char *destcopy=dest;
    while(*dest++ = *src++) 
          ;
    return destcopy;
  }

  I've traced through the application and see that it
  is calling strcpy with overlapping source and destination,
  and that the execution goes through __strcpy_ssse3,
  which seems to cause the problem.

  I made a small testcase to replicate the behavior. 
  Following http://forums.gentoo.org/viewtopic-t-840983-start-0.html,
  here is my test case:
  ------------
  $ cat strcopytest.c
  char *strcpy(char *,char *);
  int main(){ 
          char buf[80]; 
          strcpy(buf, "012345678\n"); 
          strcpy(buf, buf+1); 
          puts(buf); 
          return 0; 
  }

  $ gcc -O2 -c mystrcpy.c
  $ ld -G mystrcpy.o -o mystrcpy.so
  $ gcc strcopytest.c -o strcopytest
  $ ./strcopytest 
  12345688

  $ LD_PRELOAD=./mystrcpy.so ./strcopytest
  12345678

  ----------------

  I know that I can make my testcase work with #include "string.h",
  but the I cannot recompile the commercial application, so that's not
  a workable solution.

  ProblemType: Bug
  DistroRelease: Ubuntu 11.04
  Package: libc6 2.13-0ubuntu13
  ProcVersionSignature: Ubuntu 2.6.39-3.10-generic 2.6.39
  Uname: Linux 2.6.39-3-generic x86_64
  Architecture: amd64
  Date: Thu Jul 14 13:43:36 2011
  InstallationMedia: Ubuntu 10.04 "Lucid Lynx" - Beta amd64 (20100317.1)
  ProcEnviron:
   LANGUAGE=en_US:en
   PATH=(custom, user)
   LANG=en_US.UTF-8
   SHELL=/bin/bash
  SourcePackage: eglibc
  UpgradeStatus: Upgraded to natty on 2011-04-29 (76 days ago)

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