Use a size_t instead of an int for the byte count in BN_swap_ct().

Since bignums use ints for the same purpose, this still uses an int
internally after an overflow check.

Suggested by and discussed with jsing.
ok inoguchi, jsing

diff --git a/lib/libcrypto/bn/bn_lcl.h b/lib/libcrypto/bn/bn_lcl.h
index ad9427f..b8319dd 100644 (file)
--- a/lib/libcrypto/bn/bn_lcl.h
+++ b/lib/libcrypto/bn/bn_lcl.h
@@ -1,4 +1,4 @@
-/* $OpenBSD: bn_lcl.h,v 1.28 2018/07/10 21:52:07 tb Exp $ */
+/* $OpenBSD: bn_lcl.h,v 1.29 2018/07/23 18:14:32 tb Exp $ */
 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
  * All rights reserved.
  *
@@ -606,7 +606,7 @@ BIGNUM *BN_mod_inverse_nonct(BIGNUM *ret, const BIGNUM *a, const BIGNUM *n,
 int    BN_gcd_ct(BIGNUM *r, const BIGNUM *a, const BIGNUM *b, BN_CTX *ctx);
 int    BN_gcd_nonct(BIGNUM *r, const BIGNUM *a, const BIGNUM *b, BN_CTX *ctx);
 
-int    BN_swap_ct(BN_ULONG swap, BIGNUM *a, BIGNUM *b, int nwords);
+int    BN_swap_ct(BN_ULONG swap, BIGNUM *a, BIGNUM *b, size_t nwords);
 
 __END_HIDDEN_DECLS
 #endif

diff --git a/lib/libcrypto/bn/bn_lib.c b/lib/libcrypto/bn/bn_lib.c
index 3a468a1..0b79a87 100644 (file)
--- a/lib/libcrypto/bn/bn_lib.c
+++ b/lib/libcrypto/bn/bn_lib.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: bn_lib.c,v 1.44 2018/07/13 08:43:31 tb Exp $ */
+/* $OpenBSD: bn_lib.c,v 1.45 2018/07/23 18:14:32 tb Exp $ */
 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
  * All rights reserved.
  *
@@ -897,16 +897,19 @@ BN_consttime_swap(BN_ULONG condition, BIGNUM *a, BIGNUM *b, int nwords)
  * nwords is the number of words to swap.
  */
 int
-BN_swap_ct(BN_ULONG condition, BIGNUM *a, BIGNUM *b, int nwords)
+BN_swap_ct(BN_ULONG condition, BIGNUM *a, BIGNUM *b, size_t nwords)
 {
        BN_ULONG t;
-       int i;
+       int i, words;
 
        if (a == b)
                return 1;
-       if (bn_wexpand(a, nwords) == NULL || bn_wexpand(b, nwords) == NULL)
+       if (nwords > INT_MAX)
+               return 0;
+       words = (int)nwords;
+       if (bn_wexpand(a, words) == NULL || bn_wexpand(b, words) == NULL)
                return 0;
-       if (a->top > nwords || b->top > nwords) {
+       if (a->top > words || b->top > words) {
                BNerror(BN_R_INVALID_LENGTH);
                return 0;
        }
@@ -930,7 +933,7 @@ BN_swap_ct(BN_ULONG condition, BIGNUM *a, BIGNUM *b, int nwords)
        b->flags ^= t;
 
        /* swap the data */
-       for (i = 0; i < nwords; i++) {
+       for (i = 0; i < words; i++) {
                t = (a->d[i] ^ b->d[i]) & condition;
                a->d[i] ^= t;
                b->d[i] ^= t;