[Bug 1918035] Re: ld-2.31.so is not correctly packaged in libc6-dbg

Fri May 21 10:37:34 UTC 2021

Fixed in 2.33-0ubuntu6.

** Also affects: glibc (Ubuntu Focal)
   Importance: Undecided
       Status: New

** Also affects: glibc (Ubuntu Hirsute)
   Importance: Undecided
       Status: New

** Also affects: glibc (Ubuntu Groovy)
   Importance: Undecided
       Status: New

** Changed in: glibc (Ubuntu)
       Status: New => Fix Released

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Title:
  ld-2.31.so is not correctly packaged in libc6-dbg

Status in glibc package in Ubuntu:
  Fix Released
Status in glibc source package in Focal:
  New
Status in glibc source package in Groovy:
  New
Status in glibc source package in Hirsute:
  New

Bug description:
  lsb_release -rd
  Description:    Ubuntu 20.04.2 LTS
  Release:        20.04

  Using gdb 9.2-0ubuntu1~20.04, libc6 and libc6-dbg 2.31-0ubuntu9.2

  gdb -q /bin/date
  Reading symbols from /bin/date...
  (No debugging symbols found in /bin/date)
  (gdb) starti
  Starting program: /usr/bin/date

  Program stopped.
  0x00007ffff7fd0100 in ?? () from /lib64/ld-linux-x86-64.so.2

  (gdb) b _dl_debug_state
  Breakpoint 1 at 0x7ffff7fe11d0
  (gdb) c
  Continuing.

  Breakpoint 1, 0x00007ffff7fe11d0 in _dl_debug_state () from /lib64/ld-linux-x86-64.so.2
  (gdb) bt
  #0  0x00007ffff7fe11d0 in _dl_debug_state () from /lib64/ld-linux-x86-64.so.2
  #1  0x00007ffff7fd2fd1 in ?? () from /lib64/ld-linux-x86-64.so.2
  #2  0x00007ffff7febc3b in ?? () from /lib64/ld-linux-x86-64.so.2
  #3  0x00007ffff7fd104c in ?? () from /lib64/ld-linux-x86-64.so.2
  #4  0x00007ffff7fd0108 in ?? () from /lib64/ld-linux-x86-64.so.2
  #5  0x0000000000000001 in ?? ()
  #6  0x00007fffffffe58c in ?? ()
  #7  0x0000000000000000 in ?? ()

  Note that debug info for ld-linux is missing despite libc6-dbg being
  installed.

  (gdb) disable 1
  (gdb) catch syscall exit_group
  Catchpoint 2 (syscall 'exit_group' [231])

  (gdb) c
  Continuing.
  Sat Mar  6 22:47:08 PST 2021

  Catchpoint 2 (call to syscall exit_group), __GI__exit (status=status at entry=0) at ../sysdeps/unix/sysv/linux/_exit.c:31
  31      ../sysdeps/unix/sysv/linux/_exit.c: No such file or directory.

  Note that debug info for `libc.so.6` was loaded correctly, but debug
  info for ld-linux was not.

  (gdb) info shared
  From                To                  Syms Read   Shared Object Library
  0x00007ffff7fd0100  0x00007ffff7ff2674  Yes (*)     /lib64/ld-linux-x86-64.so.2
  0x00007ffff7df4630  0x00007ffff7f6920d  Yes         /lib/x86_64-linux-gnu/libc.so.6
  (*): Shared library is missing debugging information.

  ----
  As far as I can tell, this is happening because libc6-dbg installs ld-2.31.so into the wrong place:

  dpkg -L libc6-dbg | grep /ld-2.31
  /usr/lib/debug/lib/libc6-prof/x86_64-linux-gnu/ld-2.31.so
  /usr/lib/debug/lib/x86_64-linux-gnu/ld-2.31.so

  Since ld-linux resolves to /lib64/ld-linux-x86-64.so.2, GDB looks for
  debug symbols in the following paths:

  /lib64/.debug/ld-2.31.so
  /usr/lib/debug/lib64/ld-2.31.so
  /usr/lib/x86_64-linux-gnu/.debug/ld-2.31.so
  /usr/lib/debug/usr/lib/x86_64-linux-gnu/ld-2.31.so
  /usr/lib/x86_64-linux-gnu/.debug/ld-2.31.so
  /usr/lib/debug/usr/lib/x86_64-linux-gnu/ld-2.31.so

  None of these matches the actual installed path, so debug symbols are
  not loaded.

  P.S. Manually adding symbols via add-symbol-file
  /usr/lib/debug/lib/x86_64-linux-gnu/ld-2.31.so works fine, but this
  should be automatic.

  P.P.S. After running

  sudo mkdir /usr/lib/debug/lib64
  sudo ln -s /usr/lib/debug/lib/x86_64-linux-gnu/ld-2.31.so /usr/lib/debug/lib64

  things start working as expected:

  gdb -q /bin/date
  Reading symbols from /bin/date...
  (No debugging symbols found in /bin/date)
  (gdb) starti
  Starting program: /usr/bin/date

  Program stopped.
  0x00007ffff7fd0100 in _start () from /lib64/ld-linux-x86-64.so.2
  (gdb) b _dl_debug_state
  Breakpoint 1 at 0x7ffff7fe11d0: file dl-debug.c, line 73.
  (gdb) c
  Continuing.

  Breakpoint 1, __GI__dl_debug_state () at dl-debug.c:73
  73      dl-debug.c: No such file or directory.
  (gdb) bt
  #0  __GI__dl_debug_state () at dl-debug.c:73
  #1  0x00007ffff7fd2fd1 in dl_main (phdr=<optimized out>, phnum=<optimized out>, user_entry=<optimized out>, auxv=<optimized out>) at rtld.c:1661
  #2  0x00007ffff7febc3b in _dl_sysdep_start (start_argptr=start_argptr at entry=0x7fffffffe390, dl_main=dl_main at entry=0x7ffff7fd15e0 <dl_main>) at ../elf/dl-sysdep.c:252
  #3  0x00007ffff7fd104c in _dl_start_final (arg=0x7fffffffe390) at rtld.c:449
  #4  _dl_start (arg=0x7fffffffe390) at rtld.c:539
  #5  0x00007ffff7fd0108 in _start () from /lib64/ld-linux-x86-64.so.2
  #6  0x0000000000000001 in ?? ()
  #7  0x00007fffffffe5c8 in ?? ()
  #8  0x0000000000000000 in ?? ()

  ProblemType: Bug
  DistroRelease: Ubuntu 20.04
  Package: libc6-dbg 2.31-0ubuntu9.2
  Uname: Linux 5.4.72-microsoft-standard-WSL2 x86_64
  ApportVersion: 2.20.11-0ubuntu27.16
  Architecture: amd64
  CasperMD5CheckResult: skip
  Date: Sat Mar  6 22:39:51 2021
  ProcEnviron:
   TERM=xterm-256color
   PATH=(custom, no user)
   LANG=C.UTF-8
   SHELL=/bin/bash
  SourcePackage: glibc
  UpgradeStatus: No upgrade log present (probably fresh install)

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