[Bug 932621] Re: String corruption

[Sebastian Unger]

-L../tt/../../output/ppc  =>  -L../outuut/ppc  (corrupt, tt does not exist).
-L../tt/.././output/ppc  =>  -L./oututt/ppc  (corrupt)

I think the algorithm that gbuild uses is something like this

Starting from ../tt/.././output/ppc:

- Prepend the path to the config file to the path given in the config file (shared-libs/../tt/.././output/ppc)
- Starting from the beginning each time, search for "/\./" or "/[^/]+/\.\./" and remove each occurrence with "/"

At least that's how I would implement it. It's unlikely that they are
using regular expressions of course. It is likely that they simply scan
through the string and then use memcpy, memmove or strcpy move the
remainder of the string forward to effect the replacement. So I would
suspect those kind of functions. Have there been any changes in this
area between libc 2.13 and 2.15?

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https://bugs.launchpad.net/bugs/932621

Title:
  String corruption

Status in “eglibc” package in Ubuntu:
  New

Bug description:
  Hi there,

  I'm installing a 64 bit ubuntu server system with oneiric. However,
  due to https://bugs.launchpad.net/ubuntu/+source/ifupdown/+bug/905660
  I am trying to pull in ifupdown from precise. This pulls in the
  following additional packages from precise due to dependencies:

  libc-bin
  libc-dev-bin
  libc6
  libc6-dev
  libc6-dev-i386
  libc6-i386
  libnih-dbus1
  libnih1

  The oneiric version of the libc packages is 2.13-20ubuntu5.
  The precise version of the libc packages is 2.15-0ubuntu2.

  After this, a i386 application that I have installed on the machine
  breaks. The application is multi V4.2.4 from Green Hills. It is their
  proprietary compiler suite and IDE. When I use this compiler suite to
  compiler our embedded application, it fails to find a particular
  library. Upon further investigation I found that the front-end
  compiler driver (gbuild) passed the wrong library search path down to
  the compiler. The output of ldd gbuild is:

  la:~/trunk $ ldd /usr/ghs/multi424/gbuild 
          linux-gate.so.1 =>  (0xf774d000)
          libm.so.6 => /lib32/libm.so.6 (0xf7710000)
          libnsl.so.1 => /lib32/libnsl.so.1 (0xf76f7000)
          libdl.so.2 => /lib32/libdl.so.2 (0xf76f2000)
          libc.so.6 => /lib32/libc.so.6 (0xf7578000)
          /lib/ld-linux.so.2 (0xf774e000)

  With the oneiric version of the above packages, gbuild passing the
  (correct) option -L../output/ppc to the compiler. With the precise
  version of these libraries gbuild passes -L../outuut/ppc to the
  compiler. gbuild gets the path from a config file, which actually
  contains the option -L../../output/ppc, but is located one directory
  below the current working directory of the compiler invocation and is
  defined to be local to that file.

  So I suspect that gbuild recognizes the -L option and the fact that
  it's argument is a relative path (another -L in the same file with an
  absolute path is passed through correctly) and tries to strip off the
  initial ../ but something goes wrong. I also suspect that the bug only
  shows up in the 32bit version of libc on 64 bit systems, since all my
  64 bit apps seem to behave normally.

  I can modify the option in the config file to check what, if any,
  corruption occurs to different strings. Here are some results:

  -L../../output/ppc   =>  -L../outuut/ppc  (corrupted, that's the one that I found this with)
  -L../../../output/ppc   =>  -L../../output/ppc   (correct, no corruption)
  -L./../../output/ppc   =>  -Lshared-libs/.../output/ppppc  (corrupted, shared-libs is the directory that the config file resides in)
  -L./../output/ppc   => -Loutput/ppc    (correct, no corruption)
  -L.././../output/ppc  =>  -L../output/ppc    (correct, no corruption)
  -L../.././output/ppc  =>  -L../output/ppc  (correct, no corruption)

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