linux-kernel - [PATCH 5.14 102/125] sctp: fix the processing for COOKIE

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Date:   Mon,  1 Nov 2021 10:17:55 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Xin Long <lucien.xin@...il.com>,
        Marcelo Ricardo Leitner <marcelo.leitner@...il.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.14 102/125] sctp: fix the processing for COOKIE_ECHO chunk

From: Xin Long <lucien.xin@...il.com>

[ Upstream commit a64b341b8695e1c744dd972b39868371b4f68f83 ]

1. In closed state: in sctp_sf_do_5_1D_ce():

  When asoc is NULL, making packet for abort will use chunk's vtag
  in sctp_ootb_pkt_new(). But when asoc exists, vtag from the chunk
  should be verified before using peer.i.init_tag to make packet
  for abort in sctp_ootb_pkt_new(), and just discard it if vtag is
  not correct.

2. In the other states: in sctp_sf_do_5_2_4_dupcook():

  asoc always exists, but duplicate cookie_echo's vtag will be
  handled by sctp_tietags_compare() and then take actions, so before
  that we only verify the vtag for the abort sent for invalid chunk
  length.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Xin Long <lucien.xin@...il.com>
Acked-by: Marcelo Ricardo Leitner <marcelo.leitner@...il.com>
Signed-off-by: Jakub Kicinski <kuba@...nel.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 net/sctp/sm_statefuns.c | 14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

diff --git a/net/sctp/sm_statefuns.c b/net/sctp/sm_statefuns.c
index 672e5308839b..96a069d725e9 100644
--- a/net/sctp/sm_statefuns.c
+++ b/net/sctp/sm_statefuns.c
@@ -710,6 +710,9 @@ enum sctp_disposition sctp_sf_do_5_1D_ce(struct net *net,
 	struct sock *sk;
 	int error = 0;
 
+	if (asoc && !sctp_vtag_verify(chunk, asoc))
+		return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
+
 	/* If the packet is an OOTB packet which is temporarily on the
 	 * control endpoint, respond with an ABORT.
 	 */
@@ -724,7 +727,8 @@ enum sctp_disposition sctp_sf_do_5_1D_ce(struct net *net,
 	 * in sctp_unpack_cookie().
 	 */
 	if (!sctp_chunk_length_valid(chunk, sizeof(struct sctp_chunkhdr)))
-		return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
+		return sctp_sf_violation_chunklen(net, ep, asoc, type, arg,
+						  commands);
 
 	/* If the endpoint is not listening or if the number of associations
 	 * on the TCP-style socket exceed the max backlog, respond with an
@@ -2204,9 +2208,11 @@ enum sctp_disposition sctp_sf_do_5_2_4_dupcook(
 	 * enough for the chunk header.  Cookie length verification is
 	 * done later.
 	 */
-	if (!sctp_chunk_length_valid(chunk, sizeof(struct sctp_chunkhdr)))
-		return sctp_sf_violation_chunklen(net, ep, asoc, type, arg,
-						  commands);
+	if (!sctp_chunk_length_valid(chunk, sizeof(struct sctp_chunkhdr))) {
+		if (!sctp_vtag_verify(chunk, asoc))
+			asoc = NULL;
+		return sctp_sf_violation_chunklen(net, ep, asoc, type, arg, commands);
+	}
 
 	/* "Decode" the chunk.  We have no optional parameters so we
 	 * are in good shape.
-- 
2.33.0