OpenSSH hanging

[Henry Barber]

   Hi there,
   I'm having some strange behaviour from OpenSSH
   It presents itself when using the "ssh -t" / pseudo terminal.
   We are using this feature to update the wtmp and it is working fine on
   SuSE and RH, but our AIX hosts are getting hung. The first attempt is
   usually successful, but eventually, the session is hung and the CRTL-Z
   does not put the process into background.
   The ssh -v output
   OpenSSH_5.4p1, OpenSSL 0.9.8m 25 Feb 2010
   and when I run a truss:
   [snipped]
   kwrite(4, " �9E � d � � e 9 � O\b �".., 576)    = 576
   _select(5, 0x2005DC28, 0x00000000, 0x00000000, 0x00000000) = 1
   kread(4, " �8E07 y � � � } � < � �".., 8192)    = 32
   kfcntl(0, F_DUPFD, 0x00000000)                  = 5
   kfcntl(1, F_DUPFD, 0x00000000)                  = 6
   kfcntl(2, F_DUPFD, 0x00000000)                  = 7
   kioctl(5, 22528, 0x00000000, 0x00000000)        = 0
   kioctl(6, 22528, 0x00000000, 0x00000000)        = 0
   kioctl(7, 22528, 0x00000000, 0x00000000)        = 0
   kfcntl(5, F_SETFD, 0x00000001)                  = 0
   kfcntl(6, F_SETFD, 0x00000001)                  = 0
   kfcntl(7, F_SETFD, 0x00000001)                  = 0
   kioctl(6, 22528, 0x00000000, 0x00000000)        = 0
   sigprocmask(2, 0xF0277960, 0x2FF21AB0)          = 0
   _sigaction(1, 0x00000000, 0x2FF21B60)           = 0
   thread_setmymask_fast(0x00000000, 0x00000000, 0x00000000, 0x11FA00A9,
   0x00000000, 0x00000013, 0x00000000, 0x00000000) = 0x00000000
   sigprocmask(2, 0xF0277960, 0x2FF21AB0)          = 0
   _sigaction(1, 0x2FF21B50, 0x00000000)           = 0
   thread_setmymask_fast(0x00000000, 0x00000000, 0x00000000, 0x11FA00A9,
   0x00000000, 0x00000014, 0x00000000, 0x00000000) = 0x00000000
   sigprocmask(2, 0xF0277960, 0x2FF21AB0)          = 0
   _sigaction(1, 0x00000000, 0x2FF21B60)           = 0
   thread_setmymask_fast(0x00000000, 0x00000000, 0x00000000, 0x11FA00A9,
   0x00000000, 0x00000016, 0x00000000, 0x00000000) = 0x00000000
   sigprocmask(2, 0xF0277960, 0x2FF21AB0)          = 0
   _sigaction(1, 0x2FF21B50, 0x00000000)           = 0
   thread_setmymask_fast(0x00000000, 0x00000000, 0x00000000, 0x11FA00A9,
   0x00000000, 0x00000018, 0x00000000, 0x00000000) = 0x00000000
   sigprocmask(2, 0xF0277960, 0x2FF21AB0)          = 0
   _sigaction(2, 0x00000000, 0x2FF21B60)           = 0
   thread_setmymask_fast(0x00000000, 0x00000000, 0x00000000, 0x11FA00A9,
   0x00000000, 0x00000013, 0x00000000, 0x00000000) = 0x00000000
   sigprocmask(2, 0xF0277960, 0x2FF21AB0)          = 0
   _sigaction(2, 0x2FF21B50, 0x00000000)           = 0
   thread_setmymask_fast(0x00000000, 0x00000000, 0x00000000, 0x11FA00A9,
   0x00000000, 0x00000016, 0x00000000, 0x00000000) = 0x00000000
   sigprocmask(2, 0xF0277960, 0x2FF21AB0)          = 0
   _sigaction(2, 0x00000000, 0x2FF21B60)           = 0
   thread_setmymask_fast(0x00000000, 0x00000000, 0x00000000, 0x11FA00A9,
   0x00000000, 0x00000016, 0x00000000, 0x00000000) = 0x00000000
   sigprocmask(2, 0xF0277960, 0x2FF21AB0)          = 0
   _sigaction(2, 0x2FF21B50, 0x00000000)           = 0
   thread_setmymask_fast(0x00000000, 0x00000000, 0x00000000, 0x11FA00A9,
   0x00000000, 0x00000016, 0x00000000, 0x00000000) = 0x00000000
   sigprocmask(2, 0xF0277960, 0x2FF21AB0)          = 0
   _sigaction(3, 0x00000000, 0x2FF21B60)           = 0
   thread_setmymask_fast(0x00000000, 0x00000000, 0x00000000, 0x11FA00A9,
   0x00000000, 0x00000014, 0x00000000, 0x00000000) = 0x00000000
   sigprocmask(2, 0xF0277960, 0x2FF21AB0)          = 0
   _sigaction(3, 0x2FF21B50, 0x00000000)           = 0
   thread_setmymask_fast(0x00000000, 0x00000000, 0x00000000, 0x11FA00A9,
   0x00000000, 0x0000001B, 0x00000000, 0x00000000) = 0x00000000
   sigprocmask(2, 0xF0277960, 0x2FF21AB0)          = 0
   _sigaction(3, 0x00000000, 0x2FF21B60)           = 0
   thread_setmymask_fast(0x00000000, 0x00000000, 0x00000000, 0x11FA00A9,
   0x00000000, 0x00000013, 0x00000000, 0x00000000) = 0x00000000
   sigprocmask(2, 0xF0277960, 0x2FF21AB0)          = 0
   _sigaction(3, 0x2FF21B50, 0x00000000)           = 0
   thread_setmymask_fast(0x00000000, 0x00000000, 0x00000000, 0x11FA00A9,
   0x00000000, 0x00000016, 0x00000000, 0x00000000) = 0x00000000
   sigprocmask(2, 0xF0277960, 0x2FF21AB0)          = 0
   _sigaction(15, 0x00000000, 0x2FF21B60)          = 0
   thread_setmymask_fast(0x00000000, 0x00000000, 0x00000000, 0x11FA00A9,
   0x00000000, 0x00000015, 0x00000000, 0x00000000) = 0x00000000
   sigprocmask(2, 0xF0277960, 0x2FF21AB0)          = 0
   _sigaction(15, 0x2FF21B50, 0x00000000)          = 0
   thread_setmymask_fast(0x00000000, 0x00000000, 0x00000000, 0x11FA00A9,
   0x00000000, 0x00000015, 0x00000000, 0x00000000) = 0x00000000
   sigprocmask(2, 0xF0277960, 0x2FF21AB0)          = 0
   _sigaction(15, 0x00000000, 0x2FF21B60)          = 0
   thread_setmymask_fast(0x00000000, 0x00000000, 0x00000000, 0x11FA00A9,
   0x00000000, 0x00000019, 0x00000000, 0x00000000) = 0x00000000
   sigprocmask(2, 0xF0277960, 0x2FF21AB0)          = 0
   _sigaction(15, 0x2FF21B50, 0x00000000)          = 0
   thread_setmymask_fast(0x00000000, 0x00000000, 0x00000000, 0x11FA00A9,
   0x00000000, 0x0000001A, 0x00000000, 0x00000000) = 0x00000000
   sigprocmask(2, 0xF0277960, 0x2FF21AB0)          = 0
   _sigaction(28, 0x00000000, 0x2FF21B60)          = 0
   thread_setmymask_fast(0x00000000, 0x00000000, 0x00000000, 0x11FA00A9,
   0x00000000, 0x0000001E, 0x00000000, 0x00000000) = 0x00000000
   sigprocmask(2, 0xF0277960, 0x2FF21AB0)          = 0
   _sigaction(28, 0x2FF21B50, 0x00000000)          = 0
   thread_setmymask_fast(0x00000000, 0x00000000, 0x00000000, 0x11FA00A9,
   0x00000000, 0x0000001B, 0x00000000, 0x00000000) = 0x00000000
   kioctl(0, 22528, 0x00000000, 0x00000000)        = 0
   kioctl(0, 21505, 0x2FF21B50, 0x00000000)        = 0
   kioctl(0, 22528, 0x00000000, 0x00000000)        = 0
   kioctl(0, 21507, 0x2FF21B50, 0x00000000)        = 0
                                                      _select(8,
   0x2005DC28, 0x2005EBB8, 0x00000000, 0x00000000) = 1

                                            kwrite(4, " � � >9A06 �
   0 L 319 �92".., 128)        = 128
                        _select(8, 0x2005DC28, 0x2005EBB8, 0x00000000,
   0x00000000) = 1

              kread(4, " � � c � g :1D1B �11 � 9".., 8192)
    = 48

                                                               kioctl(0,
   1074295912, 0x2FF21A04, 0x00000000)        = 0
                                              getsockopt(4, 6, 1,
   0x2FF219D0, 0x2FF219D4)        = 0

                      setsockopt(4, 6, 1, 0x2FF219D0, 4)                =
   0


   ngetsockname(4, 0x2FF21480, 0x2FF21988)                = 0
                                                      setsockopt(4, 0, 3,
   0x2FF219D0, 4)                = 0

                              _select(8, 0x2005DC28, 0x2005EBB8,
   0x00000000, 0x00000000) = 1
                     kwrite(4, "96 C C F v � Q   l � �\f".., 384)
        = 384

   _select(8, 0x2005DC28, 0x2005EBB8, 0x00000000, 0x00000000)
   (sleeping...)
   Henry Barber
   Australian Development Lab
   office: +61 7 5552 4050
   mobile: +61 449 101 452