Don't allow tag number 31 in CBB_add_asn1().

Tag 31 is invalid for a short form identifier octet (single byte).
KNF a little more.

Based on BoringSSL commit 5ba305643f55d37a3e45e8388a36d50c1b2d4ff5

ok miod@

2 files changed, 27 insertions, 12 deletions

diff --git a/lib/libssl/bs_cbb.c b/lib/libssl/bs_cbb.c
index eed80916985..5546fac97f0 100644
--- a/lib/libssl/bs_cbb.c
+++ b/lib/libssl/bs_cbb.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: bs_cbb.c,v 1.4 2015/02/07 04:37:35 doug Exp $	*/
+/*	$OpenBSD: bs_cbb.c,v 1.5 2015/02/07 06:10:32 doug Exp $	*/
 /*
  * Copyright (c) 2014, Google Inc.
  *
@@ -28,9 +28,8 @@ cbb_init(CBB *cbb, uint8_t *buf, size_t cap)
 	struct cbb_buffer_st *base;
 
 	base = malloc(sizeof(struct cbb_buffer_st));
-	if (base == NULL) {
+	if (base == NULL)
 		return 0;
-	}
 
 	base->buf = buf;
 	base->len = 0;
@@ -148,7 +147,10 @@ CBB_finish(CBB *cbb, uint8_t **out_data, size_t *out_len)
 		return 0;
 
 	if (cbb->base->can_resize && (out_data == NULL || out_len == NULL))
-		/* |out_data| and |out_len| can only be NULL if the CBB is fixed. */
+		/*
+		 * |out_data| and |out_len| can only be NULL if the CBB is
+		 * fixed.
+		 */
 		return 0;
 
 	if (out_data != NULL)
@@ -187,9 +189,11 @@ CBB_flush(CBB *cbb)
 	len = cbb->base->len - child_start;
 
 	if (cbb->pending_is_asn1) {
-		/* For ASN.1 we assume that we'll only need a single byte for the length.
-		 * If that turned out to be incorrect, we have to move the contents along
-		 * in order to make space. */
+		/*
+		 * For ASN.1 we assume that we'll only need a single byte for
+		 * the length.  If that turned out to be incorrect, we have to
+		 * move the contents along in order to make space.
+		 */
 		size_t len_len;
 		uint8_t initial_length_byte;
 
@@ -217,7 +221,10 @@ CBB_flush(CBB *cbb)
 		}
 
 		if (len_len != 1) {
-			/* We need to move the contents along in order to make space. */
+			/*
+			 * We need to move the contents along in order to make
+			 * space.
+			 */
 			size_t extra_bytes = len_len - 1;
 			if (!cbb_buffer_add(cbb->base, NULL, extra_bytes))
 				return 0;
@@ -289,6 +296,10 @@ CBB_add_u24_length_prefixed(CBB *cbb, CBB *out_contents)
 int
 CBB_add_asn1(CBB *cbb, CBB *out_contents, uint8_t tag)
 {
+	/* Long form identifier octets are not supported. */
+	if ((tag & 0x1f) == 0x1f)
+		return 0;
+
 	if (!CBB_flush(cbb) || !CBB_add_u8(cbb, tag))
 		return 0;
 
@@ -370,8 +381,10 @@ CBB_add_asn1_uint64(CBB *cbb, uint64_t value)
 				/* Don't encode leading zeros. */
 				continue;
 
-			/* If the high bit is set, add a padding byte to make it
-			 * unsigned. */
+			/*
+			 * If the high bit is set, add a padding byte to make it
+			 * unsigned.
+			 */
 			if ((byte & 0x80) && !CBB_add_u8(&child, 0))
 				return 0;
 
diff --git a/lib/libssl/bytestring.h b/lib/libssl/bytestring.h
index 209bb38e24a..93c3df6f107 100644
--- a/lib/libssl/bytestring.h
+++ b/lib/libssl/bytestring.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: bytestring.h,v 1.3 2015/02/07 02:02:28 doug Exp $	*/
+/*	$OpenBSD: bytestring.h,v 1.4 2015/02/07 06:10:32 doug Exp $	*/
 /*
  * Copyright (c) 2014, Google Inc.
  *
@@ -374,7 +374,9 @@ int CBB_add_u24_length_prefixed(CBB *cbb, CBB *out_contents);
 /*
  * CBB_add_asn sets |*out_contents| to a |CBB| into which the contents of an
  * ASN.1 object can be written. The |tag| argument will be used as the tag for
- * the object. It returns one on success or zero on error.
+ * the object. Passing in |tag| number 31 will return in an error since only
+ * single octet identifiers are supported. It returns one on success or zero
+ * on error.
  */
 int CBB_add_asn1(CBB *cbb, CBB *out_contents, uint8_t tag);