netdev - [PATCH net 4/4] sctp: add param size validation for SCTP_PARAM_SET

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Message-Id: <e39b372644b6e5bf48df25e54b9172f34ec223a1.1624904195.git.marcelo.leitner@gmail.com>
Date:   Mon, 28 Jun 2021 16:13:44 -0300
From:   Marcelo Ricardo Leitner <marcelo.leitner@...il.com>
To:     netdev@...r.kernel.org
Cc:     linux-sctp@...r.kernel.org,
        Ilja Van Sprundel <ivansprundel@...ctive.com>,
        Neil Horman <nhorman@...driver.com>,
        Vlad Yasevich <vyasevich@...il.com>,
        Xin Long <lucien.xin@...il.com>
Subject: [PATCH net 4/4] sctp: add param size validation for SCTP_PARAM_SET_PRIMARY

When SCTP handles an INIT chunk, it calls for example:
sctp_sf_do_5_1B_init
  sctp_verify_init
    sctp_verify_param
  sctp_process_init
    sctp_process_param
      handling of SCTP_PARAM_SET_PRIMARY

sctp_verify_init() wasn't doing proper size validation and neither the
later handling, allowing it to work over the chunk itself, possibly being
uninitialized memory.

Signed-off-by: Marcelo Ricardo Leitner <marcelo.leitner@...il.com>
---
 net/sctp/sm_make_chunk.c | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/net/sctp/sm_make_chunk.c b/net/sctp/sm_make_chunk.c
index f33a870b483da7123e2ddb4473b6200a1aca5ade..587fb3cb88e29f53148cd21f13a2a86487ce292b 100644
--- a/net/sctp/sm_make_chunk.c
+++ b/net/sctp/sm_make_chunk.c
@@ -2166,9 +2166,16 @@ static enum sctp_ierror sctp_verify_param(struct net *net,
 		break;
 
 	case SCTP_PARAM_SET_PRIMARY:
-		if (ep->asconf_enable)
-			break;
-		goto unhandled;
+		if (!ep->asconf_enable)
+			goto unhandled;
+
+		if (ntohs(param.p->length) < sizeof(struct sctp_addip_param) +
+					     sizeof(struct sctp_paramhdr)) {
+			sctp_process_inv_paramlength(asoc, param.p,
+						     chunk, err_chunk);
+			retval = SCTP_IERROR_ABORT;
+		}
+		break;
 
 	case SCTP_PARAM_HOST_NAME_ADDRESS:
 		/* Tell the peer, we won't support this param.  */
-- 
2.31.1