bn/asm/rsaz-avx2.pl: fix digit correction bug in rsaz_1024_mul_avx2.
Credit to OSS-Fuzz for finding this.
CVE-2017-3738
@@ -217,7 +217,7 @@ $code.=<<___;
vmovdqu 32*8-128($ap), $ACC8
lea 192(%rsp), $tp0 # 64+128=192
- vpbroadcastq .Land_mask(%rip), $AND_MASK
+ vmovdqu .Land_mask(%rip), $AND_MASK
jmp .LOOP_GRANDE_SQR_1024
.align 32
@@ -1067,10 +1067,10 @@ $code.=<<___;
vpmuludq 32*6-128($np),$Yi,$TEMP1
vpaddq $TEMP1,$ACC6,$ACC6
vpmuludq 32*7-128($np),$Yi,$TEMP2
- vpblendd \$3, $ZERO, $ACC9, $ACC9 # correct $ACC3
+ vpblendd \$3, $ZERO, $ACC9, $TEMP1 # correct $ACC3
vpaddq $TEMP2,$ACC7,$ACC7
vpmuludq 32*8-128($np),$Yi,$TEMP0
- vpaddq $ACC9, $ACC3, $ACC3 # correct $ACC3
+ vpaddq $TEMP1, $ACC3, $ACC3 # correct $ACC3
vpaddq $TEMP0,$ACC8,$ACC8
mov %rbx, %rax
@@ -1083,7 +1083,9 @@ $code.=<<___;
vmovdqu -8+32*2-128($ap),$TEMP2
mov $r1, %rax
+ vpblendd \$0xfc, $ZERO, $ACC9, $ACC9 # correct $ACC3
imull $n0, %eax
+ vpaddq $ACC9,$ACC4,$ACC4 # correct $ACC3
and \$0x1fffffff, %eax
imulq 16-128($ap),%rbx
@@ -1319,15 +1321,12 @@ ___
# But as we underutilize resources, it's possible to correct in
# each iteration with marginal performance loss. But then, as
# we do it in each iteration, we can correct less digits, and
-# avoid performance penalties completely. Also note that we
-# correct only three digits out of four. This works because
-# most significant digit is subjected to less additions.
+# avoid performance penalties completely.
$TEMP0 = $ACC9;
$TEMP3 = $Bi;
$TEMP4 = $Yi;
$code.=<<___;
- vpermq \$0, $AND_MASK, $AND_MASK
vpaddq (%rsp), $TEMP1, $ACC0
vpsrlq \$29, $ACC0, $TEMP1
@@ -1774,7 +1773,7 @@ $code.=<<___;
.align 64
.Land_mask:
- .quad 0x1fffffff,0x1fffffff,0x1fffffff,-1
+ .quad 0x1fffffff,0x1fffffff,0x1fffffff,0x1fffffff
.Lscatter_permd:
.long 0,2,4,6,7,7,7,7
.Lgather_permd:
