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_0_2b~54
X-Git-Url: https://git.openssl.org/gitweb/?p=openssl.git;a=commitdiff_plain;h=0a59e2dc308e6d6a7078e6b3e4e714101a2db538

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>
(cherry picked from commit 69567687b0b7ed67831c17a010f4d46dfd059aef)
---

diff --git a/crypto/bn/asm/x86_64-mont5.pl b/crypto/bn/asm/x86_64-mont5.pl
index fa22c30b1f..820de3d6f6 100755
--- a/crypto/bn/asm/x86_64-mont5.pl
+++ b/crypto/bn/asm/x86_64-mont5.pl
@@ -3226,11 +3226,16 @@ $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