From b9435a55aaa723aabfebf9dbbe7978c2185c4cda Mon Sep 17 00:00:00 2001
From: aled-ua <bugbuster.cc@gmail.com>
Date: Sun, 22 Dec 2024 06:42:19 +0000
Subject: [PATCH] Fix vuln crash-c7c664759c840b3f1c438b7232f713b756ed640f

---
 src/kex.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/src/kex.c b/src/kex.c
index 4ca9c34c74..72f8b704c6 100644
--- a/src/kex.c
+++ b/src/kex.c
@@ -571,6 +571,11 @@ static int diffie_hellman_sha_algo(LIBSSH2_SESSION *session,
 #endif /* LIBSSH2DEBUG */
 
 
+        if(!session->hostkey) {
+            ret = _libssh2_error(session, LIBSSH2_ERROR_PROTO,
+                                 "hostkey is NULL");
+            goto clean_exit;
+        }
         if(session->hostkey->init(session, session->server_hostkey,
                                   session->server_hostkey_len,
                                   &session->server_hostkey_abstract)) {