This check doesn't make sense for EC keys. (Also it ignores the default
key size compiled into libcrypto, only looks at default_bits in openssl.cnf
and any settings in the php file, which results in bogus failures).

Index: ext/openssl/openssl.c
--- ext/openssl/openssl.c.orig
+++ ext/openssl/openssl.c
@@ -3763,7 +3763,7 @@ static EVP_PKEY * php_openssl_generate_private_key(str
 	int egdsocket, seeded;
 	EVP_PKEY * return_val = NULL;
 
-	if (req->priv_key_bits < MIN_KEY_LENGTH) {
+	if (req->priv_key_type != OPENSSL_KEYTYPE_EC && req->priv_key_bits < MIN_KEY_LENGTH) {
 		php_error_docref(NULL, E_WARNING, "Private key length must be at least %d bits, configured to %d",
 			MIN_KEY_LENGTH, req->priv_key_bits);
 		return NULL;
