sctp: fix call to SCTP_CMD_PROCESS_SACK in sctp_cmd_interpreter()

Bug introduced by commit edfee0339e681a784ebacec7e8c2dc97dc6d2839
(sctp: check src addr when processing SACK to update transport state)

Signed-off-by: Zijie Pan <zijie.pan@6wind.com>
Signed-off-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Acked-by: Vlad Yasevich <vyasevich@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/sctp/sm_sideeffect.c

@@ -1642,8 +1642,9 @@ static int sctp_cmd_interpreter(sctp_event_t event_type,
 					asoc->outqueue.outstanding_bytes;
 			sackh.num_gap_ack_blocks = 0;
 			sackh.num_dup_tsns = 0;
+			chunk->subh.sack_hdr = &sackh;
 			sctp_add_cmd_sf(commands, SCTP_CMD_PROCESS_SACK,
-					SCTP_SACKH(&sackh));
+					SCTP_CHUNK(chunk));
 			break;
 
 		case SCTP_CMD_DISCARD_PACKET: