--- rpm-5.4.15/rpmio/cpio.c.orig	2012-04-16 05:21:22.000000000 +0200
+++ rpm-5.4.15/rpmio/cpio.c	2015-01-25 15:50:23.017311712 +0100
@@ -136,7 +136,7 @@
     /*@=shiftimplementation@*/
 
     GET_NUM_FIELD(hdr->namesize, nb);
-    if (nb >= iosm->wrsize)
+    if (nb <= 0 || nb >= iosm->wrsize)
 	return IOSMERR_BAD_HEADER;
 
     /* Read file name. */