[6.0] 9e06cd754 Use strong VRND for silo unique number

[Dridi Boukelmoune]

commit 9e06cd75482d455dd00f60f086b11ce8b76d52dc
Author: Poul-Henning Kamp <phk at FreeBSD.org>
Date:   Wed Jun 6 13:11:08 2018 +0000

    Use strong VRND for silo unique number

diff --git a/bin/varnishd/storage/storage_persistent_subr.c b/bin/varnishd/storage/storage_persistent_subr.c
index 05ce65920..9f8d202af 100644
--- a/bin/varnishd/storage/storage_persistent_subr.c
+++ b/bin/varnishd/storage/storage_persistent_subr.c
@@ -45,6 +45,7 @@
 
 #include "storage/storage.h"
 
+#include "vrnd.h"
 #include "vsha256.h"
 
 #include "storage/storage_persistent.h"
@@ -280,7 +281,7 @@ smp_newsilo(struct smp_sc *sc)
 	assert(strlen(SMP_IDENT_STRING) < sizeof si->ident);
 
 	/* Choose a new random number */
-	sc->unique = random();
+	AZ(VRND_RandomCrypto(&sc->unique, sizeof sc->unique));
 
 	smp_reset_sign(&sc->idn);
 	si = sc->ident;