From: Andy Polyakov <appro@openssl.org>
Date: Wed, 20 May 2015 07:36:48 +0000 (+0200)
Subject: bn/asm/x86_64-mont5.pl: fix valgrind error.
X-Git-Tag: OpenSSL_1_1_0-pre1~1088
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=69567687b0b7ed67831c17a010f4d46dfd059aef;p=openssl

bn/asm/x86_64-mont5.pl: fix valgrind error.

bn_get_bits5 was overstepping array boundary by 1 byte. It was exclusively
read overstep and data could not have been used. The only potential problem
would be if array happens to end on the very edge of last accesible page.

Reviewed-by: Richard Levitte <levitte@openssl.org>
---

diff --git a/crypto/bn/asm/x86_64-mont5.pl b/crypto/bn/asm/x86_64-mont5.pl
index 69e81bf4dd..aa96d43e89 100755
--- a/crypto/bn/asm/x86_64-mont5.pl
+++ b/crypto/bn/asm/x86_64-mont5.pl
@@ -3231,11 +3231,16 @@ $code.=<<___;
 .type	bn_get_bits5,\@abi-omnipotent
 .align	16
 bn_get_bits5:
-	mov	$inp,%r10
+	lea	0($inp),%r10
+	lea	1($inp),%r11
 	mov	$num,%ecx
-	shr	\$3,$num
-	movzw	(%r10,$num),%eax
-	and	\$7,%ecx
+	shr	\$4,$num
+	and	\$15,%ecx
+	lea	-8(%ecx),%eax
+	cmp	\$11,%ecx
+	cmova	%r11,%r10
+	cmova	%eax,%ecx
+	movzw	(%r10,$num,2),%eax
 	shrl	%cl,%eax
 	and	\$31,%eax
 	ret