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CVE: CVE-2018-0735
Upstream-Status: Backport
Signed-off-by: Kai Kang <kai.kang@windriver.com>
From b1d6d55ece1c26fa2829e2b819b038d7b6d692b4 Mon Sep 17 00:00:00 2001
From: Pauli <paul.dale@oracle.com>
Date: Fri, 26 Oct 2018 10:54:58 +1000
Subject: [PATCH] Timing vulnerability in ECDSA signature generation
(CVE-2018-0735)
Preallocate an extra limb for some of the big numbers to avoid a reallocation
that can potentially provide a side channel.
Reviewed-by: Bernd Edlinger <bernd.edlinger@hotmail.de>
(Merged from https://github.com/openssl/openssl/pull/7486)
(cherry picked from commit 99540ec79491f59ed8b46b4edf130e17dc907f52)
---
crypto/ec/ec_mult.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/crypto/ec/ec_mult.c b/crypto/ec/ec_mult.c
index 7e1b3650e7..0e0a5e1394 100644
--- a/crypto/ec/ec_mult.c
+++ b/crypto/ec/ec_mult.c
@@ -206,8 +206,8 @@ int ec_scalar_mul_ladder(const EC_GROUP *group, EC_POINT *r,
*/
cardinality_bits = BN_num_bits(cardinality);
group_top = bn_get_top(cardinality);
- if ((bn_wexpand(k, group_top + 1) == NULL)
- || (bn_wexpand(lambda, group_top + 1) == NULL)) {
+ if ((bn_wexpand(k, group_top + 2) == NULL)
+ || (bn_wexpand(lambda, group_top + 2) == NULL)) {
ECerr(EC_F_EC_SCALAR_MUL_LADDER, ERR_R_BN_LIB);
goto err;
}
@@ -244,7 +244,7 @@ int ec_scalar_mul_ladder(const EC_GROUP *group, EC_POINT *r,
* k := scalar + 2*cardinality
*/
kbit = BN_is_bit_set(lambda, cardinality_bits);
- BN_consttime_swap(kbit, k, lambda, group_top + 1);
+ BN_consttime_swap(kbit, k, lambda, group_top + 2);
group_top = bn_get_top(group->field);
if ((bn_wexpand(s->X, group_top) == NULL)
--
2.17.0
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