[openssl-commits] [openssl] OpenSSL_1_0_2-stable update

[Matt Caswell]

The branch OpenSSL_1_0_2-stable has been updated
       via  235119f015e46a74040b78b10fd6e954f7f07774 (commit)
      from  d8908c3310240bb0efd9b17c663a8b9e47bf31dc (commit)


- Log -----------------------------------------------------------------
commit 235119f015e46a74040b78b10fd6e954f7f07774
Author: Matt Caswell <matt at openssl.org>
Date:   Thu May 24 16:12:52 2018 +0100

    The result of a ^ 0 mod -1 is 0 not 1
    
    Thanks to Guido Vranken and OSSFuzz for finding this issue.
    
    Reviewed-by: Rich Salz <rsalz at openssl.org>
    (Merged from https://github.com/openssl/openssl/pull/6355)
    
    (cherry picked from commit 4aa5b725d549b3ebc3a4f2f1c44e44a11f68752b)

-----------------------------------------------------------------------

Summary of changes:
 crypto/bn/bn_exp.c | 22 +++++++++++-----------
 1 file changed, 11 insertions(+), 11 deletions(-)

diff --git a/crypto/bn/bn_exp.c b/crypto/bn/bn_exp.c
index 40115fc..2eb393d 100644
--- a/crypto/bn/bn_exp.c
+++ b/crypto/bn/bn_exp.c
@@ -290,8 +290,8 @@ int BN_mod_exp_recp(BIGNUM *r, const BIGNUM *a, const BIGNUM *p,
 
     bits = BN_num_bits(p);
     if (bits == 0) {
-        /* x**0 mod 1 is still zero. */
-        if (BN_is_one(m)) {
+        /* x**0 mod 1, or x**0 mod -1 is still zero. */
+        if (BN_abs_is_word(m, 1)) {
             ret = 1;
             BN_zero(r);
         } else {
@@ -432,8 +432,8 @@ int BN_mod_exp_mont(BIGNUM *rr, const BIGNUM *a, const BIGNUM *p,
     }
     bits = BN_num_bits(p);
     if (bits == 0) {
-        /* x**0 mod 1 is still zero. */
-        if (BN_is_one(m)) {
+        /* x**0 mod 1, or x**0 mod -1 is still zero. */
+        if (BN_abs_is_word(m, 1)) {
             ret = 1;
             BN_zero(rr);
         } else {
@@ -733,8 +733,8 @@ int BN_mod_exp_mont_consttime(BIGNUM *rr, const BIGNUM *a, const BIGNUM *p,
      */
     bits = p->top * BN_BITS2;
     if (bits == 0) {
-        /* x**0 mod 1 is still zero. */
-        if (BN_is_one(m)) {
+        /* x**0 mod 1, or x**0 mod -1 is still zero. */
+        if (BN_abs_is_word(m, 1)) {
             ret = 1;
             BN_zero(rr);
         } else {
@@ -1247,8 +1247,8 @@ int BN_mod_exp_mont_word(BIGNUM *rr, BN_ULONG a, const BIGNUM *p,
 
     bits = BN_num_bits(p);
     if (bits == 0) {
-        /* x**0 mod 1 is still zero. */
-        if (BN_is_one(m)) {
+        /* x**0 mod 1, or x**0 mod -1 is still zero. */
+        if (BN_abs_is_word(m, 1)) {
             ret = 1;
             BN_zero(rr);
         } else {
@@ -1369,9 +1369,9 @@ int BN_mod_exp_simple(BIGNUM *r, const BIGNUM *a, const BIGNUM *p,
     }
 
     bits = BN_num_bits(p);
-   if (bits == 0) {
-        /* x**0 mod 1 is still zero. */
-        if (BN_is_one(m)) {
+    if (bits == 0) {
+        /* x**0 mod 1, or x**0 mod -1 is still zero. */
+        if (BN_abs_is_word(m, 1)) {
             ret = 1;
             BN_zero(r);
         } else {