<div dir="ltr"><div>Hello,<br><br></div><div>I see consistent SEGV when running Dropbear v2016.74 in uClinux 2.6.33 on ARMv7m-cortex-m4 processor<br></div><div>Faults happen only if client specifying HostKeyAlgorithms option.<br></div><div>Please see verbose output from client and dropbear:<br></div><div><br>[<a href="mailto:root@172.17.152.20">root@172.17.152.20</a>: ]# dropbear -V<br>Dropbear v2016.74<br><br></div>---------------------------------------- from client ---------------------------------------------------------------------------<br><div>$ssh -v -o HostKeyAlgorithms=ssh-dss <a href="mailto:root@172.17.152.20">root@172.17.152.20</a><br>OpenSSH_7.2p2 Ubuntu-4ubuntu2.1, OpenSSL 1.0.2g 1 Mar 2016<br>debug1: Reading configuration data /etc/ssh/ssh_config<br>debug1: /etc/ssh/ssh_config line 19: Applying options for *<br>debug1: Connecting to 172.17.152.20 [172.17.152.20] port 22.<br>debug1: Connection established.<br>debug1: key_load_public: No such file or directory<br>debug1: identity file /home//.ssh/id_rsa type -1<br>debug1: key_load_public: No such file or directory<br>debug1: identity file /home//.ssh/id_rsa-cert type -1<br>debug1: key_load_public: No such file or directory<br>debug1: identity file /home//.ssh/id_dsa type -1<br>debug1: key_load_public: No such file or directory<br>debug1: identity file /home//.ssh/id_dsa-cert type -1<br>debug1: key_load_public: No such file or directory<br>debug1: identity file /home//.ssh/id_ecdsa type -1<br>debug1: key_load_public: No such file or directory<br>debug1: identity file /home//.ssh/id_ecdsa-cert type -1<br>debug1: key_load_public: No such file or directory<br>debug1: identity file /home//.ssh/id_ed25519 type -1<br>debug1: key_load_public: No such file or directory<br>debug1: identity file /home//.ssh/id_ed25519-cert type -1<br>debug1: Enabling compatibility mode for protocol 2.0<br>debug1: Local version string SSH-2.0-OpenSSH_7.2p2 Ubuntu-4ubuntu2.1<br>debug1: Remote protocol version 2.0, remote software version dropbear_2016.74<br>debug1: no match: dropbear_2016.74<br>debug1: Authenticating to <a href="http://172.17.152.20:22">172.17.152.20:22</a> as 'root'<br>debug1: SSH2_MSG_KEXINIT sent<br>debug1: SSH2_MSG_KEXINIT received<br>debug1: kex: algorithm: <a href="mailto:curve25519-sha256@libssh.org">curve25519-sha256@libssh.org</a><br>debug1: kex: host key algorithm: ssh-dss<br>debug1: kex: server->client cipher: aes128-ctr MAC: hmac-sha2-256 compression: none<br>debug1: kex: client->server cipher: aes128-ctr MAC: hmac-sha2-256 compression: none<br>debug1: expecting SSH2_MSG_KEX_ECDH_REPLY<br>Connection closed by 172.17.152.20 port 22<br><br>---------------------------------------- from dropbear ---------------------------------------------------------------------------<br>[<a href="mailto:root@172.17.152.20">root@172.17.152.20</a>: ]# dropbear -v -F<br>TRACE (2934) 0.000000: enter buf_get_rsa_priv_key<br>TRACE (2934) 0.000702: enter buf_get_rsa_pub_key<br>TRACE (2934) 0.003142: leave buf_get_rsa_pub_key: success<br>TRACE (2934) 0.006667: leave buf_get_rsa_priv_key<br>TRACE (2934) 0.007364: leave loadhostkey<br>TRACE (2934) 0.008475: enter buf_get_dss_pub_key<br>TRACE (2934) 0.029568: leave buf_get_dss_pub_key: success<br>TRACE (2934) 0.030491: leave loadhostkey<br>TRACE (2934) 0.031491: enter buf_get_ecdsa_priv_key<br>TRACE (2934) 0.032079: enter buf_get_ecc_raw_pubkey<br>TRACE (2934) 0.037565: leave buf_get_ecdsa_pub_key<br>TRACE (2934) 0.038492: leave loadhostkey<br>TRACE (2934) 0.049830: Disabling key type 2<br>TRACE (2934) 0.050450: Disabling key type 3<br>TRACE (2934) 0.110221: listensockets: 1 to try<br>TRACE (2934) 0.111137: listening on ':22'<br>TRACE (2934) 0.111844: enter dropbear_listen<br>TRACE (2934) 0.112368: dropbear_listen: all interfaces<br>TRACE (2934) 0.113916: bind(22) failed<br>TRACE (2934) 0.114629: leave dropbear_listen: success, 1 socks bound<br>TRACE (2934) 0.115578: set_listen_fast_open failed for socket 3: Protocol not available<br>[2934] Jan 01 00:16:07 Not backgrounding<br>[2934] Jan 01 00:16:12 Child connection from <a href="http://172.17.163.3:42180">172.17.163.3:42180</a><br>TRACE (2934) 5.057261: enter session_init<br>TRACE (2934) 5.058028: setnonblocking: 5<br>TRACE (2934) 5.058726: leave setnonblocking<br>TRACE (2934) 5.059736: setnonblocking: 5<br>TRACE (2934) 5.060404: leave setnonblocking<br>TRACE (2934) 5.060983: update_channel_prio<br>TRACE (2934) 5.061525: update_channel_prio: not any<br>TRACE (2934) 5.062037: Dropbear priority transitioning 10 -> 11<br>TRACE (2934) 5.062814: setnonblocking: 3<br>TRACE (2934) 5.063414: leave setnonblocking<br>TRACE (2934) 5.063894: setnonblocking: 6<br>TRACE (2934) 5.064461: leave setnonblocking<br>TRACE (2934) 5.065835: leave session_init<br>TRACE (2934) 5.066793: kexinitialise()<br>TRACE (2934) 5.067877: DATAALLOWED=0<br>TRACE (2934) 5.068411: -> KEXINIT<br>TRACE (2934) 5.069399: enter set_connect_fds<br>TRACE (2934) 5.070012: maybe_empty_reply_queue - no data allowed<br>TRACE (2934) 5.070558: enter handle_connect_fds<br>TRACE (2934) 5.071036: leave handle_connect_fds - end iter<br>TRACE (2934) 5.071895: empty queue dequeing<br>TRACE (2934) 5.073045: enter set_connect_fds<br>TRACE (2934) 5.073657: enter ident_readln<br>TRACE (2934) 5.077698: leave ident_readln: return 40<br>TRACE (2934) 5.078328: remoteident: SSH-2.0-OpenSSH_7.2p2 Ubuntu-4ubuntu2.1<br>TRACE (2934) 5.079270: maybe_empty_reply_queue - no data allowed<br>TRACE (2934) 5.079801: enter handle_connect_fds<br>TRACE (2934) 5.080287: leave handle_connect_fds - end iter<br>TRACE (2934) 5.080824: enter set_connect_fds<br>TRACE (2934) 5.081611: process_packet: packet type = 20, len 1048<br>TRACE (2934) 5.082330: got expected packet 20 during kexinit<br>TRACE (2934) 5.082944: <- KEXINIT<br>TRACE (2934) 5.083440: enter recv_msg_kexinit<br>TRACE (2934) 5.084130: buf_match_algo: <a href="mailto:curve25519-sha256@libssh.org">curve25519-sha256@libssh.org</a>,ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group-exchange-sha256,diffie-hellman-group-exchange-sha1,diffie-hellman-group14-sha1,ext-info-c<br>TRACE (2934) 5.084896: kexguess2 1<br>TRACE (2934) 5.085457: kex algo <a href="mailto:curve25519-sha256@libssh.org">curve25519-sha256@libssh.org</a><br>TRACE (2934) 5.086025: buf_match_algo: ssh-dss<br>TRACE (2934) 5.086588: hostkey algo ssh-dss<br>TRACE (2934) 5.087174: buf_match_algo: <a href="mailto:chacha20-poly1305@openssh.com">chacha20-poly1305@openssh.com</a>,aes128-ctr,aes192-ctr,aes256-ctr,<a href="mailto:aes128-gcm@openssh.com">aes128-gcm@openssh.com</a>,<a href="mailto:aes256-gcm@openssh.com">aes256-gcm@openssh.com</a>,aes128-cbc,aes192-cbc,aes256-cbc,3des-cbc<br>TRACE (2934) 5.087844: enc c2s is aes128-ctr<br>TRACE (2934) 5.088424: buf_match_algo: <a href="mailto:chacha20-poly1305@openssh.com">chacha20-poly1305@openssh.com</a>,aes128-ctr,aes192-ctr,aes256-ctr,<a href="mailto:aes128-gcm@openssh.com">aes128-gcm@openssh.com</a>,<a href="mailto:aes256-gcm@openssh.com">aes256-gcm@openssh.com</a>,aes128-cbc,aes192-cbc,aes256-cbc,3des-cbc<br>TRACE (2934) 5.089247: enc s2c is aes128-ctr<br>TRACE (2934) 5.089838: buf_match_algo: <a href="mailto:umac-64-etm@openssh.com">umac-64-etm@openssh.com</a>,<a href="mailto:umac-128-etm@openssh.com">umac-128-etm@openssh.com</a>,<a href="mailto:hmac-sha2-256-etm@openssh.com">hmac-sha2-256-etm@openssh.com</a>,<a href="mailto:hmac-sha2-512-etm@openssh.com">hmac-sha2-512-etm@openssh.com</a>,<a href="mailto:hmac-sha1-etm@openssh.com">hmac-sha1-etm@openssh.com</a>,<a href="mailto:umac-64@openssh.com">umac-64@openssh.com</a>,<a href="mailto:umac-128@openssh.com">umac-128@openssh.com</a>,hmac-sha2-256,hmac-sha2-512,hmac-sha1<br>TRACE (2934) 5.090572: hash c2s is hmac-sha2-256<br>TRACE (2934) 5.091158: buf_match_algo: <a href="mailto:umac-64-etm@openssh.com">umac-64-etm@openssh.com</a>,<a href="mailto:umac-128-etm@openssh.com">umac-128-etm@openssh.com</a>,<a href="mailto:hmac-sha2-256-etm@openssh.com">hmac-sha2-256-etm@openssh.com</a>,<a href="mailto:hmac-sha2-512-etm@openssh.com">hmac-sha2-512-etm@openssh.com</a>,<a href="mailto:hmac-sha1-etm@openssh.com">hmac-sha1-etm@openssh.com</a>,<a href="mailto:umac-64@openssh.com">umac-64@openssh.com</a>,<a href="mailto:umac-128@openssh.com">umac-128@openssh.com</a>,hmac-sha2-256,hmac-sha2-512,hmac-sha1<br>TRACE (2934) 5.091877: hash s2c is hmac-sha2-256<br>TRACE (2934) 5.092456: buf_match_algo: none,<a href="mailto:zlib@openssh.com">zlib@openssh.com</a>,zlib<br>TRACE (2934) 5.093025: hash c2s is none<br>TRACE (2934) 5.093598: buf_match_algo: none,<a href="mailto:zlib@openssh.com">zlib@openssh.com</a>,zlib<br>TRACE (2934) 5.094179: hash s2c is none<br>TRACE (2934) 5.094836: leave recv_msg_kexinit<br>TRACE (2934) 5.095394: maybe_empty_reply_queue - no data allowed<br>TRACE (2934) 5.095885: enter handle_connect_fds<br>TRACE (2934) 5.096379: leave handle_connect_fds - end iter<br>TRACE (2934) 5.096902: enter set_connect_fds<br>TRACE (2934) 5.097611: process_packet: packet type = 30, len 42<br>TRACE (2934) 5.098344: got expected packet 30 during kexinit<br>TRACE (2934) 5.099060: enter recv_msg_kexdh_init<br>TRACE (2934) 5.099589: enter send_msg_kexdh_reply<br>TRACE (2934) 5.234566: enter buf_put_dss_sign<br>TRACE (2934) 5.336603: leave buf_put_dss_sign<br>TRACE (2934) 5.337367: leave send_msg_kexdh_reply<br>TRACE (2934) 5.337903: enter send_msg_newkeys<br>TRACE (2934) 5.338527: enter gen_new_keys<br>Aiee, segfault! You should probably report this as a bug to the developer<br>[<a href="mailto:root@172.17.152.20">root@172.17.152.20</a>: ]# <br><br><br>---------------------------------------- from client ---------------------------------------------------------------------------<br>$ ssh -v -o HostKeyAlgorithms=ssh-rsa <a href="mailto:root@172.17.152.20">root@172.17.152.20</a><br>OpenSSH_7.2p2 Ubuntu-4ubuntu2.1, OpenSSL 1.0.2g 1 Mar 2016<br>debug1: Reading configuration data /etc/ssh/ssh_config<br>debug1: /etc/ssh/ssh_config line 19: Applying options for *<br>debug1: Connecting to 172.17.152.20 [172.17.152.20] port 22.<br>debug1: Connection established.<br>debug1: key_load_public: No such file or directory<br>debug1: identity file /home//.ssh/id_rsa type -1<br>debug1: key_load_public: No such file or directory<br>debug1: identity file /home//.ssh/id_rsa-cert type -1<br>debug1: key_load_public: No such file or directory<br>debug1: identity file /home//.ssh/id_dsa type -1<br>debug1: key_load_public: No such file or directory<br>debug1: identity file /home//.ssh/id_dsa-cert type -1<br>debug1: key_load_public: No such file or directory<br>debug1: identity file /home//.ssh/id_ecdsa type -1<br>debug1: key_load_public: No such file or directory<br>debug1: identity file /home//.ssh/id_ecdsa-cert type -1<br>debug1: key_load_public: No such file or directory<br>debug1: identity file /home//.ssh/id_ed25519 type -1<br>debug1: key_load_public: No such file or directory<br>debug1: identity file /home//.ssh/id_ed25519-cert type -1<br>debug1: Enabling compatibility mode for protocol 2.0<br>debug1: Local version string SSH-2.0-OpenSSH_7.2p2 Ubuntu-4ubuntu2.1<br>debug1: Remote protocol version 2.0, remote software version dropbear_2016.74<br>debug1: no match: dropbear_2016.74<br>debug1: Authenticating to <a href="http://172.17.152.20:22">172.17.152.20:22</a> as 'root'<br>debug1: SSH2_MSG_KEXINIT sent<br>debug1: SSH2_MSG_KEXINIT received<br>debug1: kex: algorithm: <a href="mailto:curve25519-sha256@libssh.org">curve25519-sha256@libssh.org</a><br>debug1: kex: host key algorithm: ssh-rsa<br>debug1: kex: server->client cipher: aes128-ctr MAC: hmac-sha2-256 compression: none<br>debug1: kex: client->server cipher: aes128-ctr MAC: hmac-sha2-256 compression: none<br>debug1: expecting SSH2_MSG_KEX_ECDH_REPLY<br>Connection closed by 172.17.152.20 port 22<br><br>---------------------------------------- from dropbear
---------------------------------------------------------------------------<br>[<a href="mailto:root@172.17.152.20">root@172.17.152.20</a>: ]# dropbear -v -F<br>TRACE (3066) 0.000000: enter buf_get_rsa_priv_key<br>TRACE (3066) 0.000692: enter buf_get_rsa_pub_key<br>TRACE (3066) 0.003467: leave buf_get_rsa_pub_key: success<br>TRACE (3066) 0.007054: leave buf_get_rsa_priv_key<br>TRACE (3066) 0.007749: leave loadhostkey<br>TRACE (3066) 0.008958: enter buf_get_dss_pub_key<br>TRACE (3066) 0.011581: leave buf_get_dss_pub_key: success<br>TRACE (3066) 0.012362: leave loadhostkey<br>TRACE (3066) 0.013428: enter buf_get_ecdsa_priv_key<br>TRACE (3066) 0.014002: enter buf_get_ecc_raw_pubkey<br>TRACE (3066) 0.019249: leave buf_get_ecdsa_pub_key<br>TRACE (3066) 0.020103: leave loadhostkey<br>TRACE (3066) 0.020569: Disabling key type 2<br>TRACE (3066) 0.021071: Disabling key type 3<br>TRACE (3066) 0.059965: listensockets: 1 to try<br>TRACE (3066) 0.061012: listening on ':22'<br>TRACE (3066) 0.061761: enter dropbear_listen<br>TRACE (3066) 0.062337: dropbear_listen: all interfaces<br>TRACE (3066) 0.064058: bind(22) failed<br>TRACE (3066) 0.064837: leave dropbear_listen: success, 1 socks bound<br>TRACE (3066) 0.065962: set_listen_fast_open failed for socket 3: Protocol not available<br>[3066] Jan 01 00:18:21 Not backgrounding<br>[3066] Jan 01 00:18:23 Child connection from <a href="http://172.17.163.3:42554">172.17.163.3:42554</a><br>TRACE (3066) 2.443367: enter session_init<br>TRACE (3066) 2.444121: setnonblocking: 5<br>TRACE (3066) 2.444770: leave setnonblocking<br>TRACE (3066) 2.445351: setnonblocking: 5<br>TRACE (3066) 2.445970: leave setnonblocking<br>TRACE (3066) 2.446569: update_channel_prio<br>TRACE (3066) 2.447120: update_channel_prio: not any<br>TRACE (3066) 2.447636: Dropbear priority transitioning 10 -> 11<br>TRACE (3066) 2.448406: setnonblocking: 3<br>TRACE (3066) 2.449024: leave setnonblocking<br>TRACE (3066) 2.449518: setnonblocking: 6<br>TRACE (3066) 2.450104: leave setnonblocking<br>TRACE (3066) 2.451526: leave session_init<br>TRACE (3066) 2.452468: kexinitialise()<br>TRACE (3066) 2.453758: DATAALLOWED=0<br>TRACE (3066) 2.454296: -> KEXINIT<br>TRACE (3066) 2.454825: enter set_connect_fds<br>TRACE (3066) 2.455418: maybe_empty_reply_queue - no data allowed<br>TRACE (3066) 2.455931: enter handle_connect_fds<br>TRACE (3066) 2.456436: leave handle_connect_fds - end iter<br>TRACE (3066) 2.457321: empty queue dequeing<br>TRACE (3066) 2.458488: enter set_connect_fds<br>TRACE (3066) 2.459096: enter ident_readln<br>TRACE (3066) 2.463414: leave ident_readln: return 40<br>TRACE (3066) 2.464057: remoteident: SSH-2.0-OpenSSH_7.2p2 Ubuntu-4ubuntu2.1<br>TRACE (3066) 2.464651: maybe_empty_reply_queue - no data allowed<br>TRACE (3066) 2.465149: enter handle_connect_fds<br>TRACE (3066) 2.465624: leave handle_connect_fds - end iter<br>TRACE (3066) 2.466161: enter set_connect_fds<br>TRACE (3066) 2.466961: process_packet: packet type = 20, len 1048<br>TRACE (3066) 2.467688: got expected packet 20 during kexinit<br>TRACE (3066) 2.468301: <- KEXINIT<br>TRACE (3066) 2.468759: enter recv_msg_kexinit<br>TRACE (3066) 2.469425: buf_match_algo: <a href="mailto:curve25519-sha256@libssh.org">curve25519-sha256@libssh.org</a>,ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group-exchange-sha256,diffie-hellman-group-exchange-sha1,diffie-hellman-group14-sha1,ext-info-c<br>TRACE (3066) 2.470150: kexguess2 1<br>TRACE (3066) 2.470744: kex algo <a href="mailto:curve25519-sha256@libssh.org">curve25519-sha256@libssh.org</a><br>TRACE (3066) 2.471337: buf_match_algo: ssh-rsa<br>TRACE (3066) 2.471917: hostkey algo ssh-rsa<br>TRACE (3066) 2.472489: buf_match_algo: <a href="mailto:chacha20-poly1305@openssh.com">chacha20-poly1305@openssh.com</a>,aes128-ctr,aes192-ctr,aes256-ctr,<a href="mailto:aes128-gcm@openssh.com">aes128-gcm@openssh.com</a>,<a href="mailto:aes256-gcm@openssh.com">aes256-gcm@openssh.com</a>,aes128-cbc,aes192-cbc,aes256-cbc,3des-cbc<br>TRACE (3066) 2.473777: enc c2s is aes128-ctr<br>TRACE (3066) 2.474389: buf_match_algo: <a href="mailto:chacha20-poly1305@openssh.com">chacha20-poly1305@openssh.com</a>,aes128-ctr,aes192-ctr,aes256-ctr,<a href="mailto:aes128-gcm@openssh.com">aes128-gcm@openssh.com</a>,<a href="mailto:aes256-gcm@openssh.com">aes256-gcm@openssh.com</a>,aes128-cbc,aes192-cbc,aes256-cbc,3des-cbc<br>TRACE (3066) 2.475073: enc s2c is aes128-ctr<br>TRACE (3066) 2.475668: buf_match_algo: <a href="mailto:umac-64-etm@openssh.com">umac-64-etm@openssh.com</a>,<a href="mailto:umac-128-etm@openssh.com">umac-128-etm@openssh.com</a>,<a href="mailto:hmac-sha2-256-etm@openssh.com">hmac-sha2-256-etm@openssh.com</a>,<a href="mailto:hmac-sha2-512-etm@openssh.com">hmac-sha2-512-etm@openssh.com</a>,<a href="mailto:hmac-sha1-etm@openssh.com">hmac-sha1-etm@openssh.com</a>,<a href="mailto:umac-64@openssh.com">umac-64@openssh.com</a>,<a href="mailto:umac-128@openssh.com">umac-128@openssh.com</a>,hmac-sha2-256,hmac-sha2-512,hmac-sha1<br>TRACE (3066) 2.476384: hash c2s is hmac-sha2-256<br>TRACE (3066) 2.476967: buf_match_algo: <a href="mailto:umac-64-etm@openssh.com">umac-64-etm@openssh.com</a>,<a href="mailto:umac-128-etm@openssh.com">umac-128-etm@openssh.com</a>,<a href="mailto:hmac-sha2-256-etm@openssh.com">hmac-sha2-256-etm@openssh.com</a>,<a href="mailto:hmac-sha2-512-etm@openssh.com">hmac-sha2-512-etm@openssh.com</a>,<a href="mailto:hmac-sha1-etm@openssh.com">hmac-sha1-etm@openssh.com</a>,<a href="mailto:umac-64@openssh.com">umac-64@openssh.com</a>,<a href="mailto:umac-128@openssh.com">umac-128@openssh.com</a>,hmac-sha2-256,hmac-sha2-512,hmac-sha1<br>TRACE (3066) 2.477690: hash s2c is hmac-sha2-256<br>TRACE (3066) 2.478301: buf_match_algo: none,<a href="mailto:zlib@openssh.com">zlib@openssh.com</a>,zlib<br>TRACE (3066) 2.478884: hash c2s is none<br>TRACE (3066) 2.479439: buf_match_algo: none,<a href="mailto:zlib@openssh.com">zlib@openssh.com</a>,zlib<br>TRACE (3066) 2.480033: hash s2c is none<br>TRACE (3066) 2.480702: leave recv_msg_kexinit<br>TRACE (3066) 2.481229: maybe_empty_reply_queue - no data allowed<br>TRACE (3066) 2.481743: enter handle_connect_fds<br>TRACE (3066) 2.482215: leave handle_connect_fds - end iter<br>TRACE (3066) 2.482777: enter set_connect_fds<br>TRACE (3066) 2.483639: process_packet: packet type = 30, len 42<br>TRACE (3066) 2.484336: got expected packet 30 during kexinit<br>TRACE (3066) 2.484948: enter recv_msg_kexdh_init<br>TRACE (3066) 2.485459: enter send_msg_kexdh_reply<br>TRACE (3066) 2.486015: enter buf_put_rsa_pub_key<br>TRACE (3066) 2.492135: leave buf_put_rsa_pub_key<br>TRACE (3066) 2.596695: enter buf_put_rsa_pub_key<br>TRACE (3066) 2.602879: leave buf_put_rsa_pub_key<br>TRACE (3066) 2.606368: enter buf_put_rsa_sign<br>Aiee, segfault! You should probably report this as a bug to the developer<br><br><br></div><div>Please advise how to fix the problem in Dropbear.<br><br></div><div>Please let me know if additional information is needed.<br><br></div><div>Thank you,<br></div><div>Konstantin Lazarev.<br></div></div>