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Bug#941663: openssh-server: fatal: privsep_preauth: preauth child terminated by signal 31



Package: openssh-server
Version: 1:7,9p1-10

We recently installed the latest openssl patches(https://www.debian.org/security/2019/dsa-4540 https://www.debian.org/security/2019/dsa-4539 ) on  a machine running Debian 10.1, since the upgrade, ssh connections are immediately dropped (below is an excerpt of auth.log with sshd LogLevel set to Debug)

Oct  3 08:50:24 debian sshd[8048]: debug1: Forked child 11290.
Oct  3 08:50:24 debian sshd[11290]: debug1: Set /proc/self/oom_score_adj to 0
Oct  3 08:50:24 debian sshd[11290]: debug1: rexec start in 6 out 6 newsock 6 pipe 8 sock 9
Oct  3 08:50:24 debian sshd[11290]: debug1: inetd sockets after dupping: 5, 5
Oct  3 08:50:24 debian sshd[11290]: Connection from 192.168.1.2 port 58940 on 165.112.184.218 port 22
Oct  3 08:50:24 debian sshd[11290]: debug1: Client protocol version 2.0; client software version OpenSSH_7.6p1 Ubuntu-4ubuntu0.3
Oct  3 08:50:24 debian sshd[11290]: debug1: match: OpenSSH_7.6p1 Ubuntu-4ubuntu0.3 pat OpenSSH_7.0*,OpenSSH_7.1*,OpenSSH_7.2*,OpenSSH_7.3*,OpenSSH_7.4*,OpenSSH_7.5*,OpenSSH_7.6*,OpenSSH_7.7* compat 0x04000002
Oct  3 08:50:24 debian sshd[11290]: debug1: Local version string SSH-2.0-OpenSSH_7.9p1 Debian-10
Oct  3 08:50:24 debian sshd[11290]: debug1: permanently_set_uid: 102/65534 [preauth]
Oct  3 08:50:24 debian sshd[11290]: debug1: list_hostkey_types: rsa-sha2-512,rsa-sha2-256,ssh-rsa,ecdsa-sha2-nistp256,ssh-ed25519 [preauth]
Oct  3 08:50:24 debian sshd[11290]: debug1: SSH2_MSG_KEXINIT sent [preauth]
Oct  3 08:50:24 debian sshd[11290]: debug1: SSH2_MSG_KEXINIT received [preauth]
Oct  3 08:50:24 debian sshd[11290]: debug1: kex: algorithm: curve25519-sha256 [preauth]
Oct  3 08:50:24 debian sshd[11290]: debug1: kex: host key algorithm: ecdsa-sha2-nistp256 [preauth]
Oct  3 08:50:24 debian sshd[11290]: debug1: kex: client->server cipher: chacha20-poly1305@openssh.com MAC: <implicit> compression: none [preauth]
Oct  3 08:50:24 debian sshd[11290]: debug1: kex: server->client cipher: chacha20-poly1305@openssh.com MAC: <implicit> compression: none [preauth]
Oct  3 08:50:24 debian sshd[11290]: debug1: expecting SSH2_MSG_KEX_ECDH_INIT [preauth]
Oct  3 08:50:24 debian sshd[11290]: debug1: rekey after 134217728 blocks [preauth]
Oct  3 08:50:24 debian sshd[11290]: debug1: SSH2_MSG_NEWKEYS sent [preauth]
Oct  3 08:50:24 debian sshd[11290]: debug1: expecting SSH2_MSG_NEWKEYS [preauth]
Oct  3 08:50:24 debian sshd[11290]: debug1: SSH2_MSG_NEWKEYS received [preauth]
Oct  3 08:50:24 debian sshd[11290]: debug1: rekey after 134217728 blocks [preauth]
Oct  3 08:50:24 debian sshd[11290]: debug1: KEX done [preauth]
Oct  3 08:50:24 debian sshd[11290]: debug1: userauth-request for user user service ssh-connection method none [preauth]
Oct  3 08:50:24 debian sshd[11290]: debug1: attempt 0 failures 0 [preauth]
Oct  3 08:50:24 debian sshd[11290]: debug1: PAM: initializing for "user"
Oct  3 08:50:24 debian sshd[11290]: debug1: PAM: setting PAM_RHOST to "192.168.1.2"
Oct  3 08:50:24 debian sshd[11290]: debug1: PAM: setting PAM_TTY to "ssh"
Oct  3 08:50:24 debian sshd[11290]: debug1: userauth-request for user user service ssh-connection method publickey [preauth]
Oct  3 08:50:24 debian sshd[11290]: debug1: attempt 1 failures 0 [preauth]
Oct  3 08:50:24 debian sshd[11290]: debug1: userauth_pubkey: test pkalg rsa-sha2-512 pkblob RSA SHA256:4aUmJoZ6m0NnB1TB3RFIggMUaFbQe96aod3SohrLgfw [preauth]
Oct  3 08:50:24 debian sshd[11290]: debug1: temporarily_use_uid: 1003/1003 (e=0/0)
Oct  3 08:50:24 debian sshd[11290]: debug1: trying public key file /home/user/.ssh/authorized_keys
Oct  3 08:50:24 debian sshd[11290]: debug1: Could not open authorized keys '/home/user/.ssh/authorized_keys': No such file or directory
Oct  3 08:50:24 debian sshd[11290]: debug1: restore_uid: 0/0
Oct  3 08:50:24 debian sshd[11290]: Failed publickey for user from 192.168.1.2 port 58940 ssh2: RSA SHA256:L+JSUX+UtQA5J0GjsdbG1Su6Z9YgXb6EJA0KZ+AJuos
Oct  3 08:50:24 debian sshd[11290]: debug1: userauth-request for user user service ssh-connection method publickey [preauth]
Oct  3 08:50:24 debian sshd[11290]: debug1: attempt 3 failures 2 [preauth]
Oct  3 08:50:24 debian sshd[11290]: debug1: userauth_pubkey: test pkalg rsa-sha2-512 pkblob RSA SHA256:EdnXT/x3fRm1jl7Dpz2DWz8TUYphqEB71IuQtSkk/X0 [preauth]
Oct  3 08:50:24 debian sshd[11290]: debug1: temporarily_use_uid: 1003/1003 (e=0/0)
Oct  3 08:50:24 debian sshd[11290]: debug1: trying public key file /home/user/.ssh/authorized_keys
Oct  3 08:50:24 debian sshd[11290]: debug1: Could not open authorized keys '/home/user/.ssh/authorized_keys': No such file or directory
Oct  3 08:50:24 debian sshd[11290]: debug1: restore_uid: 0/0
Oct  3 08:50:24 debian sshd[11290]: debug1: temporarily_use_uid: 1003/1003 (e=0/0)
Oct  3 08:50:24 debian sshd[11290]: debug1: trying public key file /home/user/.ssh/authorized_keys2
Oct  3 08:50:24 debian sshd[11290]: debug1: Could not open authorized keys '/home/user/.ssh/authorized_keys2': No such file or directory
Oct  3 08:50:24 debian sshd[11290]: debug1: restore_uid: 0/0
Oct  3 08:50:24 debian sshd[11290]: Failed publickey for user from 192.168.1.2 port 58940 ssh2: RSA SHA256:EdnXT/x3fRm1jl7Dpz2DWz8TUYphqEB71IuQtSkk/X0
Oct  3 08:50:30 debian sshd[11290]: debug1: userauth-request for user user service ssh-connection method password [preauth]
Oct  3 08:50:30 debian sshd[11290]: debug1: attempt 4 failures 3 [preauth]
Oct  3 08:50:30 debian sshd[11290]: debug1: PAM: password authentication accepted for user
Oct  3 08:50:30 debian sshd[11290]: debug1: do_pam_account: called
Oct  3 08:50:30 debian sshd[11290]: Accepted password for user from 192.168.1.2 port 58940 ssh2
Oct  3 08:50:30 debian sshd[11290]: debug1: monitor_child_preauth: user has been authenticated by privileged process
Oct  3 08:50:30 debian sshd[11290]: debug1: monitor_read_log: child log fd closed
Oct  3 08:50:30 debian sshd[11290]: fatal: privsep_preauth: preauth child terminated by signal 31
Oct  3 08:50:30 debian sshd[11290]: debug1: do_cleanup


Is this a known issue? What else might we do to debug?



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