Ensure |BN_div| never gives negative zero in the no_branch code.
Have |bn_correct_top| fix |bn->neg| if the input is zero so that we don't have negative zeros lying around. Thanks to Brian Smith for noticing. Change-Id: I91bcadebc8e353bb29c81c4367e85853886c8e4e Reviewed-on: https://boringssl-review.googlesource.com/9074 Reviewed-by: Adam Langley <agl@google.com> Commit-Queue: Adam Langley <agl@google.com> CQ-Verified: CQ bot account: commit-bot@chromium.org <commit-bot@chromium.org>
This commit is contained in:
parent
875bf04237
commit
899b9b19a4
@ -342,6 +342,10 @@ void bn_correct_top(BIGNUM *bn) {
|
|||||||
}
|
}
|
||||||
bn->top = tmp_top;
|
bn->top = tmp_top;
|
||||||
}
|
}
|
||||||
|
|
||||||
|
if (bn->top == 0) {
|
||||||
|
bn->neg = 0;
|
||||||
|
}
|
||||||
}
|
}
|
||||||
|
|
||||||
int BN_get_flags(const BIGNUM *bn, int flags) {
|
int BN_get_flags(const BIGNUM *bn, int flags) {
|
||||||
|
@ -1123,8 +1123,7 @@ static bool TestNegativeZero(BN_CTX *ctx) {
|
|||||||
ScopedBIGNUM a(BN_new());
|
ScopedBIGNUM a(BN_new());
|
||||||
ScopedBIGNUM b(BN_new());
|
ScopedBIGNUM b(BN_new());
|
||||||
ScopedBIGNUM c(BN_new());
|
ScopedBIGNUM c(BN_new());
|
||||||
ScopedBIGNUM d(BN_new());
|
if (!a || !b || !c) {
|
||||||
if (!a || !b || !c || !d) {
|
|
||||||
return false;
|
return false;
|
||||||
}
|
}
|
||||||
|
|
||||||
@ -1142,30 +1141,42 @@ static bool TestNegativeZero(BN_CTX *ctx) {
|
|||||||
return false;
|
return false;
|
||||||
}
|
}
|
||||||
|
|
||||||
// Test that BN_div never gives negative zero in the quotient.
|
for (int consttime = 0; consttime < 2; consttime++) {
|
||||||
if (!BN_set_word(a.get(), 1) ||
|
ScopedBIGNUM numerator(BN_new()), denominator(BN_new());
|
||||||
!BN_set_word(b.get(), 2)) {
|
if (!numerator || !denominator) {
|
||||||
return false;
|
return false;
|
||||||
}
|
}
|
||||||
BN_set_negative(a.get(), 1);
|
|
||||||
if (!BN_div(d.get(), c.get(), a.get(), b.get(), ctx)) {
|
|
||||||
return false;
|
|
||||||
}
|
|
||||||
if (!BN_is_zero(d.get()) || BN_is_negative(d.get())) {
|
|
||||||
fprintf(stderr, "Division test failed.\n");
|
|
||||||
return false;
|
|
||||||
}
|
|
||||||
|
|
||||||
// Test that BN_div never gives negative zero in the remainder.
|
if (consttime) {
|
||||||
if (!BN_set_word(b.get(), 1)) {
|
BN_set_flags(numerator.get(), BN_FLG_CONSTTIME);
|
||||||
return false;
|
BN_set_flags(denominator.get(), BN_FLG_CONSTTIME);
|
||||||
}
|
}
|
||||||
if (!BN_div(d.get(), c.get(), a.get(), b.get(), ctx)) {
|
|
||||||
return false;
|
// Test that BN_div never gives negative zero in the quotient.
|
||||||
}
|
if (!BN_set_word(numerator.get(), 1) ||
|
||||||
if (!BN_is_zero(c.get()) || BN_is_negative(c.get())) {
|
!BN_set_word(denominator.get(), 2)) {
|
||||||
fprintf(stderr, "Division test failed.\n");
|
return false;
|
||||||
return false;
|
}
|
||||||
|
BN_set_negative(numerator.get(), 1);
|
||||||
|
if (!BN_div(a.get(), b.get(), numerator.get(), denominator.get(), ctx)) {
|
||||||
|
return false;
|
||||||
|
}
|
||||||
|
if (!BN_is_zero(a.get()) || BN_is_negative(a.get())) {
|
||||||
|
fprintf(stderr, "Incorrect quotient (consttime = %d).\n", consttime);
|
||||||
|
return false;
|
||||||
|
}
|
||||||
|
|
||||||
|
// Test that BN_div never gives negative zero in the remainder.
|
||||||
|
if (!BN_set_word(denominator.get(), 1)) {
|
||||||
|
return false;
|
||||||
|
}
|
||||||
|
if (!BN_div(a.get(), b.get(), numerator.get(), denominator.get(), ctx)) {
|
||||||
|
return false;
|
||||||
|
}
|
||||||
|
if (!BN_is_zero(b.get()) || BN_is_negative(b.get())) {
|
||||||
|
fprintf(stderr, "Incorrect remainder (consttime = %d).\n", consttime);
|
||||||
|
return false;
|
||||||
|
}
|
||||||
}
|
}
|
||||||
|
|
||||||
// Test that BN_set_negative will not produce a negative zero.
|
// Test that BN_set_negative will not produce a negative zero.
|
||||||
|
@ -323,7 +323,7 @@ OPENSSL_EXPORT int BN_marshal_asn1(CBB *cbb, const BIGNUM *bn);
|
|||||||
* what you want before turning to these. */
|
* what you want before turning to these. */
|
||||||
|
|
||||||
/* bn_correct_top decrements |bn->top| until |bn->d[top-1]| is non-zero or
|
/* bn_correct_top decrements |bn->top| until |bn->d[top-1]| is non-zero or
|
||||||
* until |top| is zero. */
|
* until |top| is zero. If |bn| is zero, |bn->neg| is set to zero. */
|
||||||
OPENSSL_EXPORT void bn_correct_top(BIGNUM *bn);
|
OPENSSL_EXPORT void bn_correct_top(BIGNUM *bn);
|
||||||
|
|
||||||
/* bn_wexpand ensures that |bn| has at least |words| works of space without
|
/* bn_wexpand ensures that |bn| has at least |words| works of space without
|
||||||
|
Loading…
Reference in New Issue
Block a user