After enabling nginx early data, core will occasionally appear

[liuhaicheng]

```c
ngx_int_t
ngx_ssl_handshake(ngx_connection_t *c)
{
int n, sslerr;
ngx_err_t err;
ngx_int_t rc;

#ifdef SSL_READ_EARLY_DATA_SUCCESS
if (c->ssl->try_early_data) {
return ngx_ssl_try_early_data(c);
}
#endif

if (c->ssl->in_ocsp) {
    return ngx_ssl_ocsp_validate(c);
}

ngx_ssl_clear_error(c->log);

#if OPENSSL_VERSION_NUMBER >= 0x10101000L
SSL_CTX_set_client_hello_cb(c->ssl->session_ctx, ngx_SSL_early_cb_fn, c);
#endif

```c
int
ngx_SSL_early_cb_fn(SSL *s, int *al, void *arg) {

    int                            got_extensions;
    int                           *ext_out;
    size_t                         ext_len;
    ngx_connection_t              *c;

    c = arg;

    if (c == NULL) {
        return 1;
    }

    if (c->ssl == NULL) {
        return 1;
    }

    c->ssl->extensions_size = 0;
    c->ssl->extensions = NULL;
    got_extensions = SSL_client_hello_get1_extensions_present(s,
                                                        &ext_out,
                                                        &ext_len);
    if (!got_extensions) {
        return 1;
    }
    if (!ext_out) {
        return 1;
    }
    if (!ext_len) {
        return 1;
    }

    c->ssl->extensions = ngx_palloc(c->pool, sizeof(int) * ext_len);
    if (c->ssl->extensions != NULL) {
        c->ssl->extensions_size = ext_len;
        ngx_memcpy(c->ssl->extensions, ext_out, sizeof(int) * ext_len);
    }

    OPENSSL_free(ext_out);

    return 1;
}

Probably the reason for core is that c->ssl->extensions = ngx_palloc(c->pool, sizeof(int) * ext_len); The pool of connection has been released

solution:
SSL_CTX_set_client_hello_cb does not pass the args parameter. In ngx_SSL_early_cb_fn, use the built-in c = ngx_ssl_get_connection(s) of nginx to obtain the connection, and the core problem can be solved