explicit_bzero for asn1 objects on free. Too often these contain sensitive information

and they should not be a performance bottleneck
ok miod@ krw@

1 files changed, 27 insertions, 24 deletions

diff --git a/src/lib/libcrypto/asn1/a_object.c b/src/lib/libcrypto/asn1/a_object.c
index fcd6aa91fe..5bf450d0e1 100644
--- a/src/lib/libcrypto/asn1/a_object.c
+++ b/src/lib/libcrypto/asn1/a_object.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: a_object.c,v 1.25 2016/03/06 18:05:00 beck Exp $ */
+/* $OpenBSD: a_object.c,v 1.26 2016/03/17 03:51:49 beck Exp $ */
 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
  * All rights reserved.
  *
@@ -225,23 +225,29 @@ i2t_ASN1_OBJECT(char *buf, int buf_len, ASN1_OBJECT *a)
 int
 i2a_ASN1_OBJECT(BIO *bp, ASN1_OBJECT *a)
 {
-        char buf[80], *p = buf;
-        int i;
+        char *tmp = NULL;
+        size_t tlen = 256;
+        int i = -1;
 
         if ((a == NULL) || (a->data == NULL))
-                return(BIO_write(bp, "NULL",4));
-        i = i2t_ASN1_OBJECT(buf, sizeof buf, a);
-        if (i > (int)(sizeof(buf) - 1)) {
-                p = malloc(i + 1);
-                if (!p)
+                return(BIO_write(bp, "NULL", 4));
+        if ((tmp = malloc(tlen)) == NULL)
+                return -1;
+        i = i2t_ASN1_OBJECT(tmp, tlen, a);
+        if (i > (int)(tlen - 1)) {
+                explicit_bzero(tmp, tlen);
+                free(tmp);
+                if ((tmp = malloc(i + 1)) == NULL)
                         return -1;
-                i2t_ASN1_OBJECT(p, i + 1, a);
+                tlen = i + 1;
+                i = i2t_ASN1_OBJECT(tmp, tlen, a);
         }
         if (i <= 0)
-                return BIO_write(bp, "<INVALID>", 9);
-        BIO_write(bp, p, i);
-        if (p != buf)
-                free(p);
+                i = BIO_write(bp, "<INVALID>", 9);
+        else
+                i = BIO_write(bp, tmp, i);
+        explicit_bzero(tmp, tlen);
+        free(tmp);
         return (i);
 }
 
@@ -317,18 +323,15 @@ c2i_ASN1_OBJECT(ASN1_OBJECT **a, const unsigned char **pp, long len)
         p = *pp;
         /* detach data from object */
         data = (unsigned char *)ret->data;
-        ret->data = NULL;
-        /* once detached we can change it */
-        if ((data == NULL) || (ret->length < length)) {
-                ret->length = 0;
-                free(data);
-                data = malloc(length);
-                if (data == NULL) {
-                        i = ERR_R_MALLOC_FAILURE;
-                        goto err;
-                }
-                ret->flags |= ASN1_OBJECT_FLAG_DYNAMIC_DATA;
+        if (data != NULL)
+                explicit_bzero(data, ret->length);
+        free(data);
+        data = malloc(length);
+        if (data == NULL) {
+                i = ERR_R_MALLOC_FAILURE;
+                goto err;
         }
+        ret->flags |= ASN1_OBJECT_FLAG_DYNAMIC_DATA;
         memcpy(data, p, length);
         /* reattach data to object, after which it remains const */
         ret->data = data;