Subject: Null-pointer exception during the key exchange

Null-pointer exception during the key exchange

From: Jerome Zimmermann <Jerome.Zimmermann_at_ipetronik.com>
Date: Thu, 19 Oct 2017 18:35:20 +0200

Hello list,

we are using the libssh2 v1.4.3 (with openssl 0.9.7m) since a while and try now to update to the current libssh2 v1.8.0 (with openssl 1.1.0c).

Each time when I try to make a connection to the SFTP-Server we get an null-pointer exception by reading.

Here the call-stack for the sake of completeness:

----------------------------------------------------------------------------------------------------
Unhandled exception at (0x806505a8) 0x0064F5A8 belongs to _EVP_DigestUpdate (libssh2:digest.obj)

==[Register dump]==

eax = 0000000000 ebx = 2432032460
ecx = 2432084620 edx = 0000000021

esp = 0x90f55d6c ebp = 0x90f55de8
esi = 0x90f6aa7c edi = 0x90f6aa8c
eip = 0x806505a8

==[Stacktrace]==
[0] called from (0x8064a1f9) 0x006491F9 belongs to _kex_method_diffie_hellman_group_exchange_sha256_key_exchange (libssh2:kex.obj)
[1] called from (0x8064a3db) 0x006493DB belongs to __libssh2_kex_exchange (libssh2:kex.obj)
[2] called from (0x8064397c) 0x0064297C belongs to _session_startup (libssh2:session.obj)
[3] called from (0x80642fa7) 0x00641FA7 belongs to _libssh2_session_handshake (libssh2:session.obj)
[4] called from (0x802c7c8d) 0x002C6C8D belongs to ?Connect_at_CSSHClient (SSHClient.obj)
[5] called from (0x8031e95c) 0x0031D95C belongs to xxxxx
[6] called from (0x802df20b) 0x002DE20B belongs to xxxxx
[7] called from (0x802dfab7) 0x002DEAB7 belongs to xxxxx
[8] called from (0x802df16a) 0x002DE16A belongs to xxxxx
[9] called from (0x802b7637) 0x002B6637 belongs to xxxxx
----------------------------------------------------------------------------------------------------

However, before the (EVP_MD_CTX *) ctx parameter becomes null after calling libssh2_sha256_init (here function EVP_DigestInit returns with 0).

What I am doing wrong or is missing?

Best regards

Impressum/Imprint: https://www.ipetronik.com/impressum

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Received on 2017-10-19