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Date:      Sun, 13 Dec 2020 23:51:51 +0000 (UTC)
From:      Michael Tuexen <tuexen@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org
Subject:   svn commit: r368622 - head/sys/netinet
Message-ID:  <202012132351.0BDNppv3008796@repo.freebsd.org>
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Author: tuexen
Date: Sun Dec 13 23:51:51 2020
New Revision: 368622
URL: https://svnweb.freebsd.org/changeset/base/368622

Log:
  Harden the handling of outgoing streams in case of an restart or INIT
  collision. This avouds an out-of-bounce access in case the peer can
  break the cookie signature. Thanks to Felix Wilhelm from Google for
  reporting the issue.
  
  MFC after:		1 week

Modified:
  head/sys/netinet/sctp_input.c

Modified: head/sys/netinet/sctp_input.c
==============================================================================
--- head/sys/netinet/sctp_input.c	Sun Dec 13 23:32:50 2020	(r368621)
+++ head/sys/netinet/sctp_input.c	Sun Dec 13 23:51:51 2020	(r368622)
@@ -1699,7 +1699,9 @@ sctp_process_cookie_existing(struct mbuf *m, int iphle
 			    NULL);
 		}
 		asoc->my_rwnd = ntohl(initack_cp->init.a_rwnd);
-		asoc->pre_open_streams = ntohs(initack_cp->init.num_outbound_streams);
+		if (asoc->pre_open_streams < asoc->streamoutcnt) {
+			asoc->pre_open_streams = asoc->streamoutcnt;
+		}
 
 		if (ntohl(init_cp->init.initiate_tag) != asoc->peer_vtag) {
 			/*
@@ -1831,7 +1833,9 @@ sctp_process_cookie_existing(struct mbuf *m, int iphle
 			/* move to OPEN state, if not in SHUTDOWN_SENT */
 			SCTP_SET_STATE(stcb, SCTP_STATE_OPEN);
 		}
-		asoc->pre_open_streams = ntohs(initack_cp->init.num_outbound_streams);
+		if (asoc->pre_open_streams < asoc->streamoutcnt) {
+			asoc->pre_open_streams = asoc->streamoutcnt;
+		}
 		asoc->init_seq_number = ntohl(initack_cp->init.initial_tsn);
 		asoc->sending_seq = asoc->asconf_seq_out = asoc->str_reset_seq_out = asoc->init_seq_number;
 		asoc->asconf_seq_out_acked = asoc->asconf_seq_out - 1;
@@ -2108,7 +2112,6 @@ sctp_process_cookie_new(struct mbuf *m, int iphlen, in
 	/* process the INIT-ACK info (my info) */
 	asoc->my_vtag = ntohl(initack_cp->init.initiate_tag);
 	asoc->my_rwnd = ntohl(initack_cp->init.a_rwnd);
-	asoc->pre_open_streams = ntohs(initack_cp->init.num_outbound_streams);
 	asoc->init_seq_number = ntohl(initack_cp->init.initial_tsn);
 	asoc->sending_seq = asoc->asconf_seq_out = asoc->str_reset_seq_out = asoc->init_seq_number;
 	asoc->asconf_seq_out_acked = asoc->asconf_seq_out - 1;

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