sctp: Fix malformed "Invalid Stream Identifier" error

The "Invalid Stream Identifier" error has a 16 bit reserved
field at the end, thus making the parameter length be 8 bytes.
We've never supplied that reserved field making wireshark
tag the packet as malformed.

Reported-by: Chris Dischino <cdischino@sonusnet.com>
Signed-off-by: Vlad Yasevich <vladislav.yasevich@hp.com>

include/net/sctp/sm.h

@@ -243,7 +243,8 @@ struct sctp_chunk *sctp_make_op_error(const struct sctp_association *,
 				 const struct sctp_chunk *chunk,
 				 __be16 cause_code,
 				 const void *payload,
-				 size_t paylen);
+				 size_t paylen,
+				 size_t reserve_tail);
 
 struct sctp_chunk *sctp_make_asconf_update_ip(struct sctp_association *,
 					      union sctp_addr *,

net/sctp/sm_make_chunk.c

@@ -987,7 +987,10 @@ static void *sctp_addto_param(struct sctp_chunk *chunk, int len,
 
 	target = skb_put(chunk->skb, len);
 
-	memcpy(target, data, len);
+	if (data)
+		memcpy(target, data, len);
+	else
+		memset(target, 0, len);
 
 	/* Adjust the chunk length field.  */
 	chunk->chunk_hdr->length = htons(chunklen + len);
@@ -1129,16 +1132,18 @@ nodata:
 struct sctp_chunk *sctp_make_op_error(const struct sctp_association *asoc,
 				 const struct sctp_chunk *chunk,
 				 __be16 cause_code, const void *payload,
-				 size_t paylen)
+				 size_t paylen, size_t reserve_tail)
 {
 	struct sctp_chunk *retval;
 
-	retval = sctp_make_op_error_space(asoc, chunk, paylen);
+	retval = sctp_make_op_error_space(asoc, chunk, paylen + reserve_tail);
 	if (!retval)
 		goto nodata;
 
-	sctp_init_cause(retval, cause_code, paylen);
+	sctp_init_cause(retval, cause_code, paylen + reserve_tail);
 	sctp_addto_chunk(retval, paylen, payload);
+	if (reserve_tail)
+		sctp_addto_param(retval, reserve_tail, NULL);
 
 nodata:
 	return retval;

net/sctp/sm_statefuns.c

@@ -1720,7 +1720,7 @@ static sctp_disposition_t sctp_sf_do_dupcook_a(const struct sctp_endpoint *ep,
 
 		err = sctp_make_op_error(asoc, chunk,
 					 SCTP_ERROR_COOKIE_IN_SHUTDOWN,
-					 NULL, 0);
+					 NULL, 0, 0);
 		if (err)
 			sctp_add_cmd_sf(commands, SCTP_CMD_REPLY,
 					SCTP_CHUNK(err));
@@ -3977,7 +3977,7 @@ sctp_disposition_t sctp_sf_eat_auth(const struct sctp_endpoint *ep,
 			err_chunk = sctp_make_op_error(asoc, chunk,
 							SCTP_ERROR_UNSUP_HMAC,
 							&auth_hdr->hmac_id,
-							sizeof(__u16));
+							sizeof(__u16), 0);
 			if (err_chunk) {
 				sctp_add_cmd_sf(commands, SCTP_CMD_REPLY,
 						SCTP_CHUNK(err_chunk));
@@ -4069,7 +4069,8 @@ sctp_disposition_t sctp_sf_unk_chunk(const struct sctp_endpoint *ep,
 		hdr = unk_chunk->chunk_hdr;
 		err_chunk = sctp_make_op_error(asoc, unk_chunk,
 					       SCTP_ERROR_UNKNOWN_CHUNK, hdr,
-					       WORD_ROUND(ntohs(hdr->length)));
+					       WORD_ROUND(ntohs(hdr->length)),
+					       0);
 		if (err_chunk) {
 			sctp_add_cmd_sf(commands, SCTP_CMD_REPLY,
 					SCTP_CHUNK(err_chunk));
@@ -4088,7 +4089,8 @@ sctp_disposition_t sctp_sf_unk_chunk(const struct sctp_endpoint *ep,
 		hdr = unk_chunk->chunk_hdr;
 		err_chunk = sctp_make_op_error(asoc, unk_chunk,
 					       SCTP_ERROR_UNKNOWN_CHUNK, hdr,
-					       WORD_ROUND(ntohs(hdr->length)));
+					       WORD_ROUND(ntohs(hdr->length)),
+					       0);
 		if (err_chunk) {
 			sctp_add_cmd_sf(commands, SCTP_CMD_REPLY,
 					SCTP_CHUNK(err_chunk));
@@ -6052,7 +6054,8 @@ static int sctp_eat_data(const struct sctp_association *asoc,
 
 		err = sctp_make_op_error(asoc, chunk, SCTP_ERROR_INV_STRM,
 					 &data_hdr->stream,
-					 sizeof(data_hdr->stream));
+					 sizeof(data_hdr->stream),
+					 sizeof(u16));
 		if (err)
 			sctp_add_cmd_sf(commands, SCTP_CMD_REPLY,
 					SCTP_CHUNK(err));