session_server_ssh: make hash buffer static to avoid large call stack

Author: Michal Struwe

src/session_server_ssh.c

@@ -625,10 +625,12 @@ static int
 nc_server_ssh_compare_password(const char *stored_pw, const char *received_pw)
 {
     char *received_pw_hash = NULL;
-    struct crypt_data cdata = {0};
+    static struct crypt_data cdata;
 
     NC_CHECK_ARG_RET(NULL, stored_pw, received_pw, 1);
 
+    memset(&cdata, 0, sizeof(struct crypt_data));
+
     if (!stored_pw[0]) {
         if (!received_pw[0]) {
             WRN(NULL, "User authentication successful with an empty password!");