svn commit: r277805 - head/sys/netinet

[Xin LI]

Author: delphij
Date: Tue Jan 27 19:35:38 2015
New Revision: 277805
URL: https://svnweb.freebsd.org/changeset/base/277805

Log:
  Fix SCTP stream reset vulnerability.
  
  We would like to acknowledge Gerasimos Dimitriadis who reported
  the issue and Michael Tuexen who analyzed and provided the
  fix.
  
  Security:	FreeBSD-SA-15:03.sctp
  Security:	CVE-2014-8613
  Submitted by:	tuexen

Modified:
  head/sys/netinet/sctp_input.c

Modified: head/sys/netinet/sctp_input.c
==============================================================================
--- head/sys/netinet/sctp_input.c	Tue Jan 27 19:35:36 2015	(r277804)
+++ head/sys/netinet/sctp_input.c	Tue Jan 27 19:35:38 2015	(r277805)
@@ -3649,6 +3649,9 @@ sctp_handle_stream_reset_response(struct
 					/* huh ? */
 					return (0);
 				}
+				if (ntohs(respin->ph.param_length) < sizeof(struct sctp_stream_reset_response_tsn)) {
+					return (0);
+				}
 				if (action == SCTP_STREAM_RESET_RESULT_PERFORMED) {
 					resp = (struct sctp_stream_reset_response_tsn *)respin;
 					asoc->stream_reset_outstanding--;
@@ -4037,7 +4040,7 @@ __attribute__((noinline))
 	    sctp_handle_stream_reset(struct sctp_tcb *stcb, struct mbuf *m, int offset,
         struct sctp_chunkhdr *ch_req)
 {
-	int chk_length, param_len, ptype;
+	uint16_t remaining_length, param_len, ptype;
 	struct sctp_paramhdr pstore;
 	uint8_t cstore[SCTP_CHUNK_BUFFER_SIZE];
 	uint32_t seq = 0;
@@ -4050,7 +4053,7 @@ __attribute__((noinline))
 	int num_param = 0;
 
 	/* now it may be a reset or a reset-response */
-	chk_length = ntohs(ch_req->chunk_length);
+	remaining_length = ntohs(ch_req->chunk_length) - sizeof(struct sctp_chunkhdr);
 
 	/* setup for adding the response */
 	sctp_alloc_a_chunk(stcb, chk);
@@ -4088,20 +4091,27 @@ strres_nochunk:
 	ch->chunk_length = htons(chk->send_size);
 	SCTP_BUF_LEN(chk->data) = SCTP_SIZE32(chk->send_size);
 	offset += sizeof(struct sctp_chunkhdr);
-	while ((size_t)chk_length >= sizeof(struct sctp_stream_reset_tsn_request)) {
+	while (remaining_length >= sizeof(struct sctp_paramhdr)) {
 		ph = (struct sctp_paramhdr *)sctp_m_getptr(m, offset, sizeof(pstore), (uint8_t *) & pstore);
-		if (ph == NULL)
+		if (ph == NULL) {
+			/* TSNH */
 			break;
+		}
 		param_len = ntohs(ph->param_length);
-		if (param_len < (int)sizeof(struct sctp_stream_reset_tsn_request)) {
-			/* bad param */
+		if ((param_len > remaining_length) ||
+		    (param_len < (sizeof(struct sctp_paramhdr) + sizeof(uint32_t)))) {
+			/* bad parameter length */
 			break;
 		}
-		ph = (struct sctp_paramhdr *)sctp_m_getptr(m, offset, min(param_len, (int)sizeof(cstore)),
+		ph = (struct sctp_paramhdr *)sctp_m_getptr(m, offset, min(param_len, sizeof(cstore)),
 		    (uint8_t *) & cstore);
+		if (ph == NULL) {
+			/* TSNH */
+			break;
+		}
 		ptype = ntohs(ph->param_type);
 		num_param++;
-		if (param_len > (int)sizeof(cstore)) {
+		if (param_len > sizeof(cstore)) {
 			trunc = 1;
 		} else {
 			trunc = 0;
@@ -4113,6 +4123,9 @@ strres_nochunk:
 		if (ptype == SCTP_STR_RESET_OUT_REQUEST) {
 			struct sctp_stream_reset_out_request *req_out;
 
+			if (param_len < sizeof(struct sctp_stream_reset_out_request)) {
+				break;
+			}
 			req_out = (struct sctp_stream_reset_out_request *)ph;
 			num_req++;
 			if (stcb->asoc.stream_reset_outstanding) {
@@ -4126,12 +4139,18 @@ strres_nochunk:
 		} else if (ptype == SCTP_STR_RESET_ADD_OUT_STREAMS) {
 			struct sctp_stream_reset_add_strm *str_add;
 
+			if (param_len < sizeof(struct sctp_stream_reset_add_strm)) {
+				break;
+			}
 			str_add = (struct sctp_stream_reset_add_strm *)ph;
 			num_req++;
 			sctp_handle_str_reset_add_strm(stcb, chk, str_add);
 		} else if (ptype == SCTP_STR_RESET_ADD_IN_STREAMS) {
 			struct sctp_stream_reset_add_strm *str_add;
 
+			if (param_len < sizeof(struct sctp_stream_reset_add_strm)) {
+				break;
+			}
 			str_add = (struct sctp_stream_reset_add_strm *)ph;
 			num_req++;
 			sctp_handle_str_reset_add_out_strm(stcb, chk, str_add);
@@ -4156,6 +4175,9 @@ strres_nochunk:
 			struct sctp_stream_reset_response *resp;
 			uint32_t result;
 
+			if (param_len < sizeof(struct sctp_stream_reset_response)) {
+				break;
+			}
 			resp = (struct sctp_stream_reset_response *)ph;
 			seq = ntohl(resp->response_seq);
 			result = ntohl(resp->result);
@@ -4167,7 +4189,11 @@ strres_nochunk:
 			break;
 		}
 		offset += SCTP_SIZE32(param_len);
-		chk_length -= SCTP_SIZE32(param_len);
+		if (remaining_length >= SCTP_SIZE32(param_len)) {
+			remaining_length -= SCTP_SIZE32(param_len);
+		} else {
+			remaining_length = 0;
+		}
 	}
 	if (num_req == 0) {
 		/* we have no response free the stuff */