netdev - [PATCH net v3] sctp: asconf's process should verify address parameter is in the beginning

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Message-Id: <a4904b1345d0e96667e8608454c225ae038acbbe.1440621325.git.lucien.xin@gmail.com>
Date:	Thu, 27 Aug 2015 04:35:25 +0800
From:	Xin Long <lucien.xin@...il.com>
To:	network dev <netdev@...r.kernel.org>
Cc:	mleitner@...hat.com, davem@...emloft.net, vyasevic@...hat.com
Subject: [PATCH net v3] sctp: asconf's process should verify address parameter is in the beginning

in sctp_process_asconf(), we get address parameter from the beginning of
the addip params. but we never check if it's really there. if the addr
param is not there, it still can pass sctp_verify_asconf(), then to be
handled by sctp_process_asconf(), it will not be safe.

so add a code in sctp_verify_asconf() to check the address parameter is in
the beginning, or return false to send abort.

v2->v3:
 * put the check in the loop, add the check for multiple address parameters.
v1->v2:
 * put the check behind the params' length verify.

Signed-off-by: Xin Long <lucien.xin@...il.com>
Signed-off-by: Vlad Yasevich <vyasevic@...hat.com>
---
 net/sctp/sm_make_chunk.c | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/net/sctp/sm_make_chunk.c b/net/sctp/sm_make_chunk.c
index 06320c8..4068fe1 100644
--- a/net/sctp/sm_make_chunk.c
+++ b/net/sctp/sm_make_chunk.c
@@ -3130,14 +3130,24 @@ bool sctp_verify_asconf(const struct sctp_association *asoc,
 		case SCTP_PARAM_ERR_CAUSE:
 			break;
 		case SCTP_PARAM_IPV4_ADDRESS:
+			if (addr_param_seen) {
+				/* peer placed multiple address parameters into
+				 * the same asconf. reject it.
+				 */
+				return false;
+			}
 			if (length != sizeof(sctp_ipv4addr_param_t))
 				return false;
-			addr_param_seen = true;
+			if (param.v == addip->addip_hdr.params)
+				addr_param_seen = true;
 			break;
 		case SCTP_PARAM_IPV6_ADDRESS:
+			if (addr_param_seen)
+				return false;
 			if (length != sizeof(sctp_ipv6addr_param_t))
 				return false;
-			addr_param_seen = true;
+			if (param.v == addip->addip_hdr.params)
+				addr_param_seen = true;
 			break;
 		case SCTP_PARAM_ADD_IP:
 		case SCTP_PARAM_DEL_IP:
-- 
2.1.0

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