server_config_util_ssh: make hash buffer static to avoid large call stack

Author: Michal Struwe

src/server_config_util_ssh.c

@@ -498,10 +498,12 @@ _nc_server_config_add_ssh_user_password(const struct ly_ctx *ctx, const char *tr
     int ret = 0;
     char *hashed_pw = NULL;
     const char *salt = "$6$idsizuippipk$";
-    struct crypt_data cdata = {0};
+    static struct crypt_data cdata;
 
     NC_CHECK_ARG_RET(NULL, ctx, tree_path, password, config, 1);
 
+    memset(&cdata, 0, sizeof(struct crypt_data));
+
     hashed_pw = crypt_r(password, salt, &cdata);
     if (!hashed_pw) {
         ERR(NULL, "Hashing password failed (%s).", strerror(errno));