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Bug#297264: marked as done (ssh deadlock when LogLevel is DEBUG3)

Your message dated Wed, 13 Jun 2007 11:27:35 +0100
with message-id <20070613102734.GT4163@riva.ucam.org>
and subject line Bug#297264: ssh deadlock when LogLevel is DEBUG3
has caused the attached Bug report to be marked as done.

This means that you claim that the problem has been dealt with.
If this is not the case it is now your responsibility to reopen the
Bug report if necessary, and/or fix the problem forthwith.

(NB: If you are a system administrator and have no idea what I am
talking about this indicates a serious mail system misconfiguration
somewhere.  Please contact me immediately.)

Debian bug tracking system administrator
(administrator, Debian Bugs database)
--- Begin Message --- 
Package: ssh
Version: 1:3.8.1p1-8.sarge.4
Severity: important


If I set LogLevel of sshd to DEBUG3, sometimes I get deadlock of child ssh process.
Here is backtrace (ssh was rebuilt from 3.8.1p1-8.sarge.4 source with debug
information):

#0  0x401a1604 in __pthread_sigsuspend () from /lib/libpthread.so.0
#1  0x401a13c8 in __pthread_wait_for_restart_signal () from /lib/libpthread.so.0
#2  0x401a2d99 in __pthread_alt_lock () from /lib/libpthread.so.0
#3  0x4019fba5 in pthread_mutex_lock () from /lib/libpthread.so.0
#4  0x402befcb in openlog () from /lib/libc.so.6
#5  0x080729c8 in do_log (level=SYSLOG_LEVEL_DEBUG1,
    fmt=0x80849bc "Received SIGCHLD.", args=0xbfffe104 "TZ") at ../log.c:331
#6  0x08072600 in debug (fmt=0x80849bc "Received SIGCHLD.") at ../log.c:163
#7  0x08053240 in sigchld_handler (sig=17) at ../serverloop.c:145
#8  0x401a4825 in __pthread_sighandler () from /lib/libpthread.so.0
#9  <signal handler called>
#10 0x402c33f6 in send () from /lib/libc.so.6
#11 0x402beaff in vsyslog () from /lib/libc.so.6
#12 0x402be76f in syslog () from /lib/libc.so.6
#13 0x080729e8 in do_log (level=SYSLOG_LEVEL_DEBUG2,
    fmt=0x808ef44 "channel %d: output %s -> %s", args=0xbfffeef4 "") at ../log.c:332
#14 0x08072628 in debug2 (fmt=0x808ef44 "channel %d: output %s -> %s") at ../log.c:173
#15 0x08073281 in chan_set_ostate (c=0x809b3e0, next=3) at ../nchan.c:95
#16 0x0807362e in chan_obuf_empty (c=0x809b3e0) at ../nchan.c:221
#17 0x08073a92 in chan_rcvd_ieof (c=0x809b3e0) at ../nchan.c:372
#18 0x0806e726 in channel_input_ieof (type=96, seq=10, ctxt=0x812c690)
    at ../channels.c:1914
#19 0x0807b3a0 in dispatch_run (mode=1, done=0x0, ctxt=0x812c690) at ../dispatch.c:93
#20 0x08053bc4 in process_buffered_input_packets () at ../serverloop.c:475
#21 0x0805436e in server_loop2 (authctxt=0x809ab10) at ../serverloop.c:759
#22 0x0805b875 in do_authenticated2 (authctxt=0x809ab10) at ../session.c:2212
#23 0x08057fd1 in do_authenticated (authctxt=0x809ab10) at ../session.c:226
#24 0x0804ef64 in main (ac=1, av=0x8098750) at ../sshd.c:1513


I've found following remark that I think is related to my problem:
http://rpmfind.net/linux/RPM/suse/updates/9.1/i386/rpm/i586/openssh-3.8p1-37.17.i586.html
* Mon Jun 28 2004 - meissner@suse.de
  - block sigalarm during syslog output or we might deadlock
    on recursively entering syslog(). (LTC#9523, SUSE#42354)

Regards,
    Alexandra.

-- System Information:
Debian Release: 3.1
  APT prefers testing
  APT policy: (999, 'testing'), (50, 'unstable')
Architecture: i386 (i686)
Kernel: Linux 2.4.27-2-686-smp
Locale: LANG=C, LC_CTYPE=ru_RU.UTF-8 (charmap=UTF-8)

Versions of packages ssh depends on:
ii  adduser                     3.59         Add and remove users and groups
ii  debconf                     1.4.30.11    Debian configuration management sy
ii  dpkg                        1.10.26      Package maintenance system for Deb
ii  libc6                       2.3.2.ds1-20 GNU C Library: Shared libraries an
ii  libpam-modules              0.76-22      Pluggable Authentication Modules f
ii  libpam-runtime              0.76-22      Runtime support for the PAM librar
ii  libpam0g                    0.76-22      Pluggable Authentication Modules l
ii  libssl0.9.7                 0.9.7e-2     SSL shared libraries
ii  libwrap0                    7.6.dbs-6    Wietse Venema's TCP wrappers libra
ii  zlib1g                      1:1.2.2-3    compression library - runtime

-- debconf information excluded

--- End Message ---
--- Begin Message --- 
Source: openssh
Source-Version: 1:4.6p1-1

On Mon, Feb 28, 2005 at 01:50:19PM +0300, Alexandra N. Kossovsky wrote:
> Package: ssh
> Version: 1:3.8.1p1-8.sarge.4
> Severity: important
> 
> 
> If I set LogLevel of sshd to DEBUG3, sometimes I get deadlock of child ssh process.
> Here is backtrace (ssh was rebuilt from 3.8.1p1-8.sarge.4 source with debug
> information):
> 
> #0  0x401a1604 in __pthread_sigsuspend () from /lib/libpthread.so.0
> #1  0x401a13c8 in __pthread_wait_for_restart_signal () from /lib/libpthread.so.0
> #2  0x401a2d99 in __pthread_alt_lock () from /lib/libpthread.so.0
> #3  0x4019fba5 in pthread_mutex_lock () from /lib/libpthread.so.0
> #4  0x402befcb in openlog () from /lib/libc.so.6
> #5  0x080729c8 in do_log (level=SYSLOG_LEVEL_DEBUG1,
>     fmt=0x80849bc "Received SIGCHLD.", args=0xbfffe104 "TZ") at ../log.c:331
> #6  0x08072600 in debug (fmt=0x80849bc "Received SIGCHLD.") at ../log.c:163
> #7  0x08053240 in sigchld_handler (sig=17) at ../serverloop.c:145

This was fixed in OpenSSH 4.4. The upstream changelog entry was:

   - djm@cvs.openbsd.org 2006/03/04 04:12:58
     [serverloop.c]
     move a debug() outside of a signal handler; ok markus@ a little while back

Thanks,

-- 
Colin Watson                                       [cjwatson@debian.org]

--- End Message ---
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