bn/asm/x86_64-mont.pl: fix for CVE-2016-7055 (Low severity).

Reviewed-by: Rich Salz <rsalz@openssl.org>

diff --git a/crypto/bn/asm/x86_64-mont.pl b/crypto/bn/asm/x86_64-mont.pl
index 0451fef12e952f382adbcec062e67bc18708f5b0..df4cca5bfebf0cc82a35c5951d3d379d36b11bdb 100755 (executable)
--- a/crypto/bn/asm/x86_64-mont.pl
+++ b/crypto/bn/asm/x86_64-mont.pl
@@ -1157,18 +1157,17 @@ $code.=<<___;
        mulx    2*8($aptr),%r15,%r13    # ...
        adox    -3*8($tptr),%r11
        adcx    %r15,%r12
-       adox    $zero,%r12
+       adox    -2*8($tptr),%r12
        adcx    $zero,%r13
+       adox    $zero,%r13
 
        mov     $bptr,8(%rsp)           # off-load &b[i]
-       .byte   0x67
        mov     $mi,%r15
        imulq   24(%rsp),$mi            # "t[0]"*n0
        xor     %ebp,%ebp               # xor   $zero,$zero     # cf=0, of=0
 
        mulx    3*8($aptr),%rax,%r14
         mov    $mi,%rdx
-       adox    -2*8($tptr),%r12
        adcx    %rax,%r13
        adox    -1*8($tptr),%r13
        adcx    $zero,%r14