Bug#166728: Additional information on #166728

[Stuart Anderson <anderson@netsweng.com>]

I upgraded this morning, and rendered my system unusable. 8-( but managed to
dig around a little bit before recoving the system.

I got libc6 2.3.1-3 as part of the upgrade. The biggest problem seems to be
that bash is statically linked, and all of the NSS related issues have not
been resolved. With bash crashing, any form of login (to an account which
used bash) fails, and even the system startup fails, presumably because
bash crashes.

||/ Name           Version        Description
+++-==============-==============-============================================
ii  bash           2.05b-3        The GNU Bourne Again SHell


Using strace and gdb, I was able to determine that bash was loading the NSS
library /lib/libnss_compat.so.2, which in turn loads /lib/libnsl.so.1,
and /lib/libc.so.6, and /lib/ld-linux.so.2. A SIGSEGV occurs right after that.
With GDB, I obtained the following stack:

(gdb) r
Starting program: /bin/bash

Program received signal SIGSEGV, Segmentation fault.
0x080e27a3 in _dl_relocate_object ()
(gdb) bt
#0  0x080e27a3 in _dl_relocate_object ()
#1  0x080dc9fb in dl_open_worker ()
#2  0x080ca99e in _dl_catch_error ()
#3  0x080dcc62 in _dl_open ()
#4  0x080cb2f8 in do_dlopen ()
#5  0x080ca99e in _dl_catch_error ()
#6  0x080cb2b3 in dlerror_run ()
#7  0x080cb368 in __libc_dlopen ()
#8  0x080c4765 in __nss_lookup_function ()
#9  0x080c4460 in __nss_lookup ()
#10 0x080c53cd in __nss_passwd_lookup ()
#11 0x080bf5ff in getpwuid_r ()
#12 0x080bf23f in getpwuid ()
#13 0x080499db in get_current_user_info () at shell.c:1491
#14 0x08049c02 in shell_initialize () at shell.c:1549
#15 0x08048560 in main (argc=1, argv=0xbffffd84, env=0xbffffd8c) at shell.c:507

Is perhaps something in the dynamic loader assuming that libc was loaded as
part of the main executable, such that the code path taken in the case of
a staticly linked binary hasn't been as thoroughly debugged?

One other odd thing I noticed was that if I redirected stdout to a file
instead of a tty which running bash under strace, it did not crash.


Due to the fact that the system is rendered useless, I would rate this bug as

Severity: critical


                                Stuart

Stuart R. Anderson                               anderson@netsweng.com
Network & Software Engineering                   http://www.netsweng.com/
1024D/37A79149:                                  0791 D3B8 9A4C 2CDC A31F
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