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 69e81bf4dd6ff1940da9a1026f94c031d113ebd1..aa96d43e8909ecf12250e920fdfc5dfc90071625 100755 (executable)
--- 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