From 622a531c18187e3c59a7ab2d32ab990b397aafc2 Mon Sep 17 00:00:00 2001
From: Andy Polyakov <appro@openssl.org>
Date: Sat, 13 Feb 2016 17:13:53 +0100
Subject: chacha/asm/chacha*: ensure that zero length is handled (without
 crash).

RT#4305

Reviewed-by: Rich Salz <rsalz@openssl.org>
---
 crypto/chacha/asm/chacha-x86_64.pl | 3 +++
 1 file changed, 3 insertions(+)

(limited to 'crypto/chacha/asm/chacha-x86_64.pl')

diff --git a/crypto/chacha/asm/chacha-x86_64.pl b/crypto/chacha/asm/chacha-x86_64.pl
index 1a87cf8495..107fc70819 100755
--- a/crypto/chacha/asm/chacha-x86_64.pl
+++ b/crypto/chacha/asm/chacha-x86_64.pl
@@ -219,6 +219,8 @@ $code.=<<___;
 .type	ChaCha20_ctr32,\@function,5
 .align	64
 ChaCha20_ctr32:
+	cmp	\$0,$len
+	je	.Lno_data
 	mov	OPENSSL_ia32cap_P+4(%rip),%r10
 	test	\$`1<<(41-32)`,%r10d
 	jnz	.LChaCha20_ssse3
@@ -375,6 +377,7 @@ $code.=<<___;
 	pop	%r12
 	pop	%rbp
 	pop	%rbx
+.Lno_data:
 	ret
 .size	ChaCha20_ctr32,.-ChaCha20_ctr32
 ___
-- 
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