[Bug 1577460] Re: mkinitramfs --help > Core dumped

[Martin Pitt]

I've tried (in vain so far) to understand what's going on and how this
is related to the locale-langpack/ search path patch.

Tested/reproduced with

  LC_ALL=fo_FOO gdb --args getopt -o c:d:ko:r:v -n /usr/sbin/mkinitramfs
-- --help

Some observations:

 * This crash doesn't happen with looking up LC_MESSAGES, only in this
getopt case with LC_IDENTIFICATION. The mere presence of
/usr/lib/locale/fo_FOO/LC_IDENTIFICATION in the search path causes this
crash. If *only* /usr/lib/locale/fo/LC_IDENTIFICATION gets added (and
not also the more specific fo_FOO one) then things still work.

 * In all cases the returned list from _nl_make_l10nflist() was correct
in memory, so I suppose this triggers some bug (insufficiently large
buffer or so) somewhere else. Nevertheless we need to be bug compatible
with that.

During that I also noticed some bugs in the patch:

     malloc (sizeof (*retval) + (__argz_count (dirlist, dirlist_len)
-                               * (1 << pop (mask))
+                               * 2 * (1 << pop (mask))

We shouldn't allocate 2* the number here, just argz_count() + 1, as we
are only adding one more search path.

Also we should correctly interleave lookups in /usr/share/locale-
langpack/ with /usr/share/locale wrt. the mask -- i. e. we should
*first* check if there is a more specific locale (with territory,
encoding, etc.) in /usr/share/locale-langpack/ and then check more
generic locales in both places.

But if I just fix these two bugs, then getopt still crashes on getting
too many LC_IDENTIFICATION search paths. So one proposal would be to
only do the locale-langpack/ lookup for LC_MESSAGES, not for any other
category; our langpacks only ship LC_MESSAGES anyway, so we make the
scope of this small enough to avoid triggering the crash.

** Patch added: "fixed debian/patches/ubuntu/local-altlocaledir.diff"
   https://bugs.launchpad.net/ubuntu/+source/glibc/+bug/1577460/+attachment/4755012/+files/local-altlocaledir.diff

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https://bugs.launchpad.net/bugs/1577460

Title:
  mkinitramfs --help > Core dumped

Status in Ubuntu on IBM z Systems:
  Confirmed
Status in glibc package in Ubuntu:
  Confirmed
Status in glibc source package in Xenial:
  Confirmed

Bug description:
  Problem Description
  ==============================
  root at zlin060:~# mkinitramfs --help
  Segmentation fault (core dumped)
  W: non-GNU getopt
  root at zlin060:~#

  == Comment: #9 - Heinz-Werner Seeck <heinz-werner_seeck at de.ibm.com> - 2016-05-02 10:09:34 ==
  With Ubuntu 14.40 login via ssh:

  Following cmd :
  'getopt -o c:d:ko:r:v -n /usr/sbin/mkinitramfs -- --help'

  Following call-stack occured (creates coredump):

  #0  __strncmp_c (s1=0x2e6575634a500a6d <error: Cannot access memory at address 0x2e6575634a500a6d>, 
      s1 at entry=0x2e6575634a500a6a <error: Cannot access memory at address 0x2e6575634a500a6a>, 
      s2=0x3fff7fff7ae "p", s2 at entry=0x3fff7fff7ab "gelp", n=n at entry=4) at ../string/strncmp.c:44
  #1  0x000003ff7e9d4252 in _getopt_internal_r (argc=<optimized out>, argv=0x40, 
      optstring=0x200000030 <error: Cannot access memory at address 0x200000030>, longopts=<optimized out>, 
      longind=<optimized out>, long_only=0, d=0x3ff7ea8c330 <getopt_data>, posixly_correct=0) at getopt.c:546
  #2  0x000003ff7e9d51f2 in _getopt_internal (argc=<optimized out>, argv=<optimized out>, 
      optstring=<optimized out>, longopts=<optimized out>, longind=0x3fff7ffe674, long_only=0, posixly_correct=0)
      at getopt.c:1175
  #3  0x000003ff7e9d52b6 in getopt_long (argc=<optimized out>, argv=<optimized out>, options=<optimized out>, 
      long_options=<optimized out>, opt_index=0x3fff7ffe674) at getopt1.c:65
  #4  0x000002aa236821d8 in ?? ()
  #5  0x000002aa23681c22 in main ()

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