CVE-2015-0206 (published 2015-01-09T02:59Z)

Memory leak in the dtls1_buffer_record function in d1_pkt.c in OpenSSL 1.0.0 before 1.0.0p and 1.0.1 before 1.0.1k allows remote attackers to cause a denial of service (memory consumption) by sending many duplicate records for the next epoch, leading to failure of replay detection.

Severity: MEDIUM
CVSS v2 base score: 5.0 (AV:N/AC:L/Au:N/C:N/I:N/A:P)

Weakness information:
cwe_id: CWE-119
cwe_name: Improper Restriction of Operations within the Bounds of a Memory Buffer
description: The product performs operations on a memory buffer, but it reads from or writes to a memory location outside the buffer's intended boundary. This may result in read or write operations on unexpected memory locations that could be linked to other variables, data structures, or internal program data.
extended_description: 
            Certain languages allow direct addressing of memory locations and do not automatically ensure that these locations are valid for the memory buffer that is being referenced. This can cause read or write operations to be performed on memory locations that may be associated with other variables, data structures, or internal program data.
         
         

Fix information:
repo_url: https://github.com/openssl/openssl
commit_details: repo_url: https://github.com/openssl/openssl
author: Matt Caswell
author_date: 2015-01-07 14:18:13+00:00
msg: A memory leak can occur in dtls1_buffer_record if either of the calls to
ssl3_setup_buffers or pqueue_insert fail. The former will fail if there is a
malloc failure, whilst the latter will fail if attempting to add a duplicate
record to the queue. This should never happen because duplicate records should
be detected and dropped before any attempt to add them to the queue.
Unfortunately records that arrive that are for the next epoch are not being
recorded correctly, and therefore replays are not being detected.
Additionally, these "should not happen" failures that can occur in
dtls1_buffer_record are not being treated as fatal and therefore an attacker
could exploit this by sending repeated replay records for the next epoch,
eventually causing a DoS through memory exhaustion.

Thanks to Chris Mueller for reporting this issue and providing initial
analysis and a patch. Further analysis and the final patch was performed by
Matt Caswell from the OpenSSL development team.

CVE-2015-0206

Reviewed-by: Dr Stephen Henson <steve@openssl.org>
repository: repo_url: https://github.com/openssl/openssl
repo_name: openssl/openssl
description: TLS/SSL and crypto library
repo_language: C
owner: openssl
file_changes: filename: d1_pkt.c
change_type: ModificationType.MODIFY
diff: @@ -212,7 +212,7 @@ dtls1_buffer_record(SSL *s, record_pqueue *queue, unsigned char *priority)
 	/* Limit the size of the queue to prevent DOS attacks */
 	if (pqueue_size(queue->q) >= 100)
 		return 0;
-		
+
 	rdata = OPENSSL_malloc(sizeof(DTLS1_RECORD_DATA));
 	item = pitem_new(priority, rdata);
 	if (rdata == NULL || item == NULL)
@@ -247,18 +247,22 @@ dtls1_buffer_record(SSL *s, record_pqueue *queue, unsigned char *priority)
 	if (!ssl3_setup_buffers(s))
 		{
 		SSLerr(SSL_F_DTLS1_BUFFER_RECORD, ERR_R_INTERNAL_ERROR);
+		if (rdata->rbuf.buf != NULL)
+			OPENSSL_free(rdata->rbuf.buf);
 		OPENSSL_free(rdata);
 		pitem_free(item);
-		return(0);
+		return(-1);
 		}
 
 	/* insert should not fail, since duplicates are dropped */
 	if (pqueue_insert(queue->q, item) == NULL)
 		{
 		SSLerr(SSL_F_DTLS1_BUFFER_RECORD, ERR_R_INTERNAL_ERROR);
+		if (rdata->rbuf.buf != NULL)
+			OPENSSL_free(rdata->rbuf.buf);
 		OPENSSL_free(rdata);
 		pitem_free(item);
-		return(0);
+		return(-1);
 		}
 
 	return(1);
@@ -314,8 +318,9 @@ dtls1_process_buffered_records(SSL *s)
             dtls1_get_unprocessed_record(s);
             if ( ! dtls1_process_record(s))
                 return(0);
-            dtls1_buffer_record(s, &(s->d1->processed_rcds), 
-                s->s3->rrec.seq_num);
+            if(dtls1_buffer_record(s, &(s->d1->processed_rcds),
+                s->s3->rrec.seq_num)<0)
+                return -1;
             }
         }
 
@@ -529,7 +534,6 @@ printf("\n");
 
 	/* we have pulled in a full packet so zero things */
 	s->packet_length=0;
-	dtls1_record_bitmap_update(s, &(s->d1->bitmap));/* Mark receipt of record. */
 	return(1);
 
 f_err:
@@ -563,7 +567,8 @@ int dtls1_get_record(SSL *s)
 
 	/* The epoch may have changed.  If so, process all the
 	 * pending records.  This is a non-blocking operation. */
-	dtls1_process_buffered_records(s);
+	if(dtls1_process_buffered_records(s)<0)
+		return -1;
 
 	/* if we're renegotiating, then there may be buffered records */
 	if (dtls1_get_processed_record(s))
@@ -703,7 +708,9 @@ again:
 		{
 		if ((SSL_in_init(s) || s->in_handshake) && !s->d1->listen)
 			{
-			dtls1_buffer_record(s, &(s->d1->unprocessed_rcds), rr->seq_num);
+			if(dtls1_buffer_record(s, &(s->d1->unprocessed_rcds), rr->seq_num)<0)
+				return -1;
+			dtls1_record_bitmap_update(s, bitmap);/* Mark receipt of record. */
 			}
 		rr->length = 0;
 		s->packet_length = 0;
@@ -716,6 +723,7 @@ again:
 		s->packet_length = 0;  /* dump this record */
 		goto again;   /* get another record */
 		}
+	dtls1_record_bitmap_update(s, bitmap);/* Mark receipt of record. */
 
 	return(1);
 
@@ -869,7 +877,11 @@ start:
 		 * buffer the application data for later processing rather
 		 * than dropping the connection.
 		 */
-		dtls1_buffer_record(s, &(s->d1->buffered_app_data), rr->seq_num);
+		if(dtls1_buffer_record(s, &(s->d1->buffered_app_data), rr->seq_num)<0)
+			{
+			SSLerr(SSL_F_DTLS1_READ_BYTES, ERR_R_INTERNAL_ERROR);
+			return -1;
+			}
 		rr->length = 0;
 		goto start;
 		}

programming_language: C