From: Dr. Stephen Henson <steve@openssl.org>
Date: Sun, 6 Apr 2014 22:11:20 +0000 (+0100)
Subject: Return if ssleay_rand_add called with zero num.
X-Git-Tag: OpenSSL_1_0_2-beta2~260
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=cd29ced6de9a5458764d94620588bfb5fa2624ba;p=openssl

Return if ssleay_rand_add called with zero num.

Treat a zero length passed to ssleay_rand_add a no op: the existing logic
zeroes the md value which is very bad. OpenSSL itself never does this
internally and the actual call doesn't make sense as it would be passing
zero bytes of entropy.

Thanks to Marcus Meissner <meissner@suse.de> for reporting this bug.
(cherry picked from commit 5be1ae28ef3c4bdec95b94f14e0e939157be550a)
---

diff --git a/crypto/rand/md_rand.c b/crypto/rand/md_rand.c
index dd29163727..aee1c30b0a 100644
--- a/crypto/rand/md_rand.c
+++ b/crypto/rand/md_rand.c
@@ -198,6 +198,9 @@ static void ssleay_rand_add(const void *buf, int num, double add)
 	EVP_MD_CTX m;
 	int do_not_lock;
 
+	if (!num)
+		return;
+
 	/*
 	 * (Based on the rand(3) manpage)
 	 *