Bug 1406666

+++ This bug was initially created as a clone of Bug #1197051 +++

Description of problem:

With the latest sshd in Rawhide, you can no longer log in
over ssh.

The client side dies with:

[spstarr@fedora-qa ~]$ ssh -v 127.0.0.1
OpenSSH_7.3p1, OpenSSL 1.1.0c-fips  10 Nov 2016
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: Reading configuration data /etc/ssh/ssh_config.d/05-redhat.conf
debug1: /etc/ssh/ssh_config.d/05-redhat.conf line 2: include /etc/crypto-policies/back-ends/openssh.txt matched no files
debug1: /etc/ssh/ssh_config.d/05-redhat.conf line 8: Applying options for *
debug1: Connecting to 127.0.0.1 [127.0.0.1] port 22.
debug1: Connection established.
[...]
debug1: Next authentication method: publickey
debug1: Trying private key: /home/spstarr/.ssh/id_rsa
debug1: Trying private key: /home/spstarr/.ssh/id_dsa
debug1: Trying private key: /home/spstarr/.ssh/id_ecdsa
debug1: Trying private key: /home/spstarr/.ssh/id_ed25519
debug1: Next authentication method: password
spstarr.0.1's password: 
debug1: Authentication succeeded (password).
Authenticated to 127.0.0.1 ([127.0.0.1]:22).
debug1: channel 0: new [client-session]
debug1: Requesting no-more-sessions
debug1: Entering interactive session.
debug1: pledge: network
packet_write_wait: Connection to 127.0.0.1 port 22: Broken pipe

/var/log/secure shows:

Dec 21 02:41:05 fedora-qa sshd[3458]: Accepted password for spstarr from 127.0.0.1 port 59216 ssh2
Dec 21 02:41:05 fedora-qa sshd[3458]: fatal: privsep_preauth: preauth child terminated by signal 31


I straced the server, and the sshd subprocess dies with SIGSYS:

[...]
[pid  3480] writev(2, [{iov_base="Inconsistency detected by ld.so:"..., iov_len=33}, {iov_base="dl-close.c", iov_len=10}, {iov_base=": ", iov_len=2}, {iov_base="811", iov_len=3}, {iov_base=": ", iov_len=2}, {iov_base="_dl_close", iov_len=9}, {iov_base=": ", iov_len=2}, {iov_base="Assertion `", iov_len=11}, {iov_base="map->l_init_called", iov_len=18}, {iov_base="' failed!\n", iov_len=10}], 10) = ?
[pid  3479] <... read resumed> "", 4)   = 0
[pid  3480] +++ killed by SIGSYS +++
[pid  3479] --- SIGCHLD {si_signo=SIGCHLD, si_code=CLD_KILLED, si_pid=3480, si_uid=74, si_status=SIGSYS, si_utime=1, si_stime=0} ---
[pid  3479] close(7)                    = 0
[pid  3479] close(6)                    = 0
[pid  3479] close(-1)                   = -1 EBADF (Bad file descriptor)
[pid  3479] mmap(NULL, 1310720, PROT_READ|PROT_WRITE, MAP_SHARED|MAP_ANONYMOUS, -1, 0) = 0x7fa98f235000
[pid  3479] munmap(0x7fa9985b0000, 65536) = 0
[pid  3479] wait4(3480, [{WIFSIGNALED(s) && WTERMSIG(s) == SIGSYS}], 0, NULL) = 3480
[pid  3479] getpid()                    = 3479
[pid  3479] socket(AF_UNIX, SOCK_DGRAM|SOCK_CLOEXEC, 0) = 4
[pid  3479] connect(4, {sa_family=AF_UNIX, sun_path="/dev/log"}, 110) = 0
[pid  3479] sendto(4, "<82>Dec 21 02:42:26 sshd[3479]: "..., 93, MSG_NOSIGNAL, NULL, 0) = 93
[pid  3479] close(4)                    = 0
[pid  3479] getpid()                    = 3479
[pid  3479] getuid()                    = 0
[pid  3479] socket(AF_NETLINK, SOCK_RAW, NETLINK_AUDIT) = -1 EPROTONOSUPPORT (Protocol not supported)
[pid  3479] socket(AF_NETLINK, SOCK_RAW, NETLINK_AUDIT) = -1 EPROTONOSUPPORT (Protocol not supported)
[pid  3479] socket(AF_NETLINK, SOCK_RAW, NETLINK_AUDIT) = -1 EPROTONOSUPPORT (Protocol not supported)
[pid  3479] exit_group(255)             = ?
[pid  3323] <... select resumed> )      = 1 (in [6])
[pid  3323] close(6)                    = 0
[pid  3479] +++ exited with 255 +++
select(7, [3 4], NULL, NULL, NULL)      = ? ERESTARTNOHAND (To be restarted if no handler)
--- SIGCHLD {si_signo=SIGCHLD, si_code=CLD_EXITED, si_pid=3479, si_uid=0, si_status=255, si_utime=2, si_stime=2} ---
wait4(-1, [{WIFEXITED(s) && WEXITSTATUS(s) == 255}], WNOHANG, NULL) = 3479
wait4(-1, 0x7ffd3aff7484, WNOHANG, NULL) = -1 ECHILD (No child processes)
rt_sigaction(SIGCHLD, NULL, {sa_handler=0x5569c51596b0, sa_mask=[], sa_flags=SA_RESTORER, sa_restorer=0x7f4fa4c91b20}, 8) = 0
rt_sigreturn({mask=[]})                 = -1 EINTR (Interrupted system call)

Version-Release number of selected component (if applicable):

openssh-7.3p1-7.fc26.x86_64
openssh-clients-7.3p1-7.fc26.x86_64
openssh-server-7.3p1-7.fc26.x86_64

Whats unclear to me is why this works fine on Fedora 25 with same RPMs, I even downgraded kernel to match what Fedora 25 ships with.

How reproducible:

100%

Steps to Reproduce:
1. Install openssh-server
2. Try to ssh to the machine from another or from localhost