test: fix coverity 1451534: improper use of negative value

Reviewed-by: Tomas Mraz <tomas@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/14638)

diff --git a/test/servername_test.c b/test/servername_test.c
index ddf0417bc642cb1ab651bf7647abc4fd370a0390..b417f8bcacbad6abaa55d7330d3a560b4f3bfaf7 100644 (file)
--- a/test/servername_test.c
+++ b/test/servername_test.c
@@ -52,8 +52,8 @@ static int get_sni_from_client_hello(BIO *bio, char **sni)
     memset(&pkt4, 0, sizeof(pkt4));
     memset(&pkt5, 0, sizeof(pkt5));
 
-    len = BIO_get_mem_data(bio, (char **)&data);
-    if (!TEST_true(PACKET_buf_init(&pkt, data, len))
+    if (!TEST_long_ge(len = BIO_get_mem_data(bio, (char **)&data), 0)
+            || !TEST_true(PACKET_buf_init(&pkt, data, len))
                /* Skip the record header */
             || !PACKET_forward(&pkt, SSL3_RT_HEADER_LENGTH)
                /* Skip the handshake message header */