From 22eedc9722746206bf2f8b0c5fcdab58917c7bd5 Mon Sep 17 00:00:00 2001
From: Conrad Meyer <cem@FreeBSD.org>
Date: Tue, 18 Jun 2019 18:50:58 +0000
Subject: [PATCH] random(4): Fix a regression in short AES mode reads

In r349154, random device reads of size < 16 bytes (AES block size) were
accidentally broken to loop forever.  Correct the loop condition for small
reads.

Reported by:	pho
Reviewed by:	delphij
Approved by:	secteam(delphij)
Differential Revision:	https://reviews.freebsd.org/D20686
---
 sys/dev/random/fortuna.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/sys/dev/random/fortuna.c b/sys/dev/random/fortuna.c
index f7f8a753c790..0e66ba3e97f6 100644
--- a/sys/dev/random/fortuna.c
+++ b/sys/dev/random/fortuna.c
@@ -489,7 +489,7 @@ random_fortuna_genbytes(uint8_t *buf, size_t bytecount,
 	if (!random_chachamode)
 		chunk_size = rounddown(chunk_size, RANDOM_BLOCKSIZE);
 
-	while (bytecount >= chunk_size) {
+	while (bytecount >= chunk_size && chunk_size > 0) {
 		randomdev_keystream(p_key, p_counter, buf, chunk_size);
 
 		buf += chunk_size;