use freezero() instead of memset/explicit_bzero + free. Substantially

reduces conditional logic (-218, +82).

MOD_EXP_CTIME_MIN_CACHE_LINE_WIDTH cache alignment calculation bn/bn_exp.c
wasn'tt quite right.  Two other tricky bits with ASN1_STRING_FLAG_NDEF and
BN_FLG_STATIC_DATA where the condition cannot be collapsed completely.

Passes regress.  ok beck

4 files changed, 14 insertions, 28 deletions

diff --git a/src/lib/libcrypto/bn/bn_asm.c b/src/lib/libcrypto/bn/bn_asm.c
index 49f0ba5d7b..993fbb3dc5 100644
--- a/src/lib/libcrypto/bn/bn_asm.c
+++ b/src/lib/libcrypto/bn/bn_asm.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: bn_asm.c,v 1.14 2015/02/25 15:39:49 bcook Exp $ */
+/* $OpenBSD: bn_asm.c,v 1.15 2017/05/02 03:59:44 deraadt Exp $ */
 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
  * All rights reserved.
  *
@@ -989,8 +989,7 @@ enter:
         }
         memcpy(rp, tp, num * sizeof(BN_ULONG));
 out:
-        explicit_bzero(tp, (num + 2) * sizeof(BN_ULONG));
-        free(tp);
+        freezero(tp, (num + 2) * sizeof(BN_ULONG));
         return 1;
 }
 #else
@@ -1081,8 +1080,7 @@ bn_mul_mont(BN_ULONG *rp, const BN_ULONG *ap, const BN_ULONG *bp,
         }
         memcpy(rp, tp, num * sizeof(BN_ULONG));
 out:
-        explicit_bzero(tp, (num + 2) * sizeof(BN_ULONG));
-        free(tp);
+        freezero(tp, (num + 2) * sizeof(BN_ULONG));
         return 1;
 }
 #else
diff --git a/src/lib/libcrypto/bn/bn_exp.c b/src/lib/libcrypto/bn/bn_exp.c
index d388758927..b778d5d67c 100644
--- a/src/lib/libcrypto/bn/bn_exp.c
+++ b/src/lib/libcrypto/bn/bn_exp.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: bn_exp.c,v 1.30 2017/01/29 17:49:22 beck Exp $ */
+/* $OpenBSD: bn_exp.c,v 1.31 2017/05/02 03:59:44 deraadt Exp $ */
 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
  * All rights reserved.
  *
@@ -706,12 +706,10 @@ BN_mod_exp_mont_consttime(BIGNUM *rr, const BIGNUM *a, const BIGNUM *p,
         numPowers = 1 << window;
         powerbufLen = sizeof(m->d[0]) * (top * numPowers +
             ((2*top) > numPowers ? (2*top) : numPowers));
-        if ((powerbufFree = malloc(powerbufLen +
-            MOD_EXP_CTIME_MIN_CACHE_LINE_WIDTH)) == NULL)
+        if ((powerbufFree = calloc(powerbufLen +
+            MOD_EXP_CTIME_MIN_CACHE_LINE_WIDTH, 1)) == NULL)
                 goto err;
-
         powerbuf = MOD_EXP_CTIME_ALIGN(powerbufFree);
-        memset(powerbuf, 0, powerbufLen);
 
         /* lay down tmp and am right after powers table */
         tmp.d = (BN_ULONG *)(powerbuf + sizeof(m->d[0]) * top * numPowers);
@@ -901,10 +899,7 @@ BN_mod_exp_mont_consttime(BIGNUM *rr, const BIGNUM *a, const BIGNUM *p,
 err:
         if ((in_mont == NULL) && (mont != NULL))
                 BN_MONT_CTX_free(mont);
-        if (powerbuf != NULL) {
-                explicit_bzero(powerbuf, powerbufLen);
-                free(powerbufFree);
-        }
+        freezero(powerbufFree, powerbufLen + MOD_EXP_CTIME_MIN_CACHE_LINE_WIDTH);
         BN_CTX_end(ctx);
         return (ret);
 }
diff --git a/src/lib/libcrypto/bn/bn_lib.c b/src/lib/libcrypto/bn/bn_lib.c
index f2736e31c3..8aeeb5304f 100644
--- a/src/lib/libcrypto/bn/bn_lib.c
+++ b/src/lib/libcrypto/bn/bn_lib.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: bn_lib.c,v 1.37 2017/01/29 17:49:22 beck Exp $ */
+/* $OpenBSD: bn_lib.c,v 1.38 2017/05/02 03:59:44 deraadt Exp $ */
 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
  * All rights reserved.
  *
@@ -220,10 +220,8 @@ BN_clear_free(BIGNUM *a)
         if (a == NULL)
                 return;
         bn_check_top(a);
-        if (a->d != NULL && !(BN_get_flags(a, BN_FLG_STATIC_DATA))) {
-                explicit_bzero(a->d, a->dmax * sizeof(a->d[0]));
-                free(a->d);
-        }
+        if (a->d != NULL && !(BN_get_flags(a, BN_FLG_STATIC_DATA)))
+                freezero(a->d, a->dmax * sizeof(a->d[0]));
         i = BN_get_flags(a, BN_FLG_MALLOCED);
         explicit_bzero(a, sizeof(BIGNUM));
         if (i)
@@ -393,10 +391,8 @@ bn_expand2(BIGNUM *b, int words)
                 BN_ULONG *a = bn_expand_internal(b, words);
                 if (!a)
                         return NULL;
-                if (b->d) {
-                        explicit_bzero(b->d, b->dmax * sizeof(b->d[0]));
-                        free(b->d);
-                }
+                if (b->d)
+                        freezero(b->d, b->dmax * sizeof(b->d[0]));
                 b->d = a;
                 b->dmax = words;
         }
diff --git a/src/lib/libcrypto/bn/bn_rand.c b/src/lib/libcrypto/bn/bn_rand.c
index 812fa6a575..8625757140 100644
--- a/src/lib/libcrypto/bn/bn_rand.c
+++ b/src/lib/libcrypto/bn/bn_rand.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: bn_rand.c,v 1.19 2017/01/29 17:49:22 beck Exp $ */
+/* $OpenBSD: bn_rand.c,v 1.20 2017/05/02 03:59:44 deraadt Exp $ */
 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
  * All rights reserved.
  *
@@ -186,10 +186,7 @@ bnrand(int pseudorand, BIGNUM *rnd, int bits, int top, int bottom)
         ret = 1;
 
 err:
-        if (buf != NULL) {
-                explicit_bzero(buf, bytes);
-                free(buf);
-        }
+        freezero(buf, bytes);
         bn_check_top(rnd);
         return (ret);
 }