bn/asm/x86_64-mont5.pl: fix carry bug in bn_sqr8x_internal.

CVE-2017-3732

Reviewed-by: Rich Salz <rsalz@openssl.org>
This commit is contained in:
Andy Polyakov 2017-01-21 21:30:49 +01:00 committed by Matt Caswell
parent 3e7a496307
commit 3f4bcf5bb6

View File

@ -1934,6 +1934,7 @@ __bn_sqr8x_reduction:
.align 32
.L8x_tail_done:
xor %rax,%rax
add (%rdx),%r8 # can this overflow?
adc \$0,%r9
adc \$0,%r10
@ -1941,10 +1942,8 @@ __bn_sqr8x_reduction:
adc \$0,%r12
adc \$0,%r13
adc \$0,%r14
adc \$0,%r15 # can't overflow, because we
# started with "overhung" part
# of multiplication
xor %rax,%rax
adc \$0,%r15
adc \$0,%rax
neg $carry
.L8x_no_tail:
@ -3384,6 +3383,7 @@ __bn_sqrx8x_reduction:
.align 32
.Lsqrx8x_tail_done:
xor %rax,%rax
add 24+8(%rsp),%r8 # can this overflow?
adc \$0,%r9
adc \$0,%r10
@ -3391,10 +3391,8 @@ __bn_sqrx8x_reduction:
adc \$0,%r12
adc \$0,%r13
adc \$0,%r14
adc \$0,%r15 # can't overflow, because we
# started with "overhung" part
# of multiplication
mov $carry,%rax # xor %rax,%rax
adc \$0,%r15
adc \$0,%rax
sub 16+8(%rsp),$carry # mov 16(%rsp),%cf
.Lsqrx8x_no_tail: # %cf is 0 if jumped here
@ -3409,7 +3407,7 @@ __bn_sqrx8x_reduction:
adc 8*5($tptr),%r13
adc 8*6($tptr),%r14
adc 8*7($tptr),%r15
adc %rax,%rax # top-most carry
adc \$0,%rax # top-most carry
mov 32+8(%rsp),%rbx # n0
mov 8*8($tptr,%rcx),%rdx # modulo-scheduled "%r8"