diff -ur openssl-1.0.2h/crypto/bio/bio_cb.c openssl-1.0.2h.work/crypto/bio/bio_cb.c
--- openssl-1.0.2h/crypto/bio/bio_cb.c	2016-05-03 09:44:42.000000000 -0400
+++ openssl-1.0.2h.work/crypto/bio/bio_cb.c	2016-08-15 10:15:09.316203814 -0400
@@ -77,6 +77,9 @@
         r = ret;
 
     len = BIO_snprintf(buf,sizeof buf,"BIO[%p]: ",(void *)bio);
+    if (len < 0) {
+	return len;
+    }
 
     p = buf + len;
     p_maxlen = sizeof(buf) - len;