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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Jon Maloy <jmaloy@redhat.com>,
        Tung Nguyen <tung.q.nguyen@dektech.com.au>,
        Jakub Kicinski <kuba@kernel.org>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.16 040/121] tipc: fix incorrect order of state message data sanity check
Date:   Mon, 14 Mar 2022 12:53:43 +0100
Message-Id: <20220314112745.247266147@linuxfoundation.org>
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From: Tung Nguyen <tung.q.nguyen@dektech.com.au>

[ Upstream commit c79fcc27be90b308b3fa90811aefafdd4078668c ]

When receiving a state message, function tipc_link_validate_msg()
is called to validate its header portion. Then, its data portion
is validated before it can be accessed correctly. However, current
data sanity  check is done after the message header is accessed to
update some link variables.

This commit fixes this issue by moving the data sanity check to
the beginning of state message handling and right after the header
sanity check.

Fixes: 9aa422ad3266 ("tipc: improve size validations for received domain records")
Acked-by: Jon Maloy <jmaloy@redhat.com>
Signed-off-by: Tung Nguyen <tung.q.nguyen@dektech.com.au>
Link: https://lore.kernel.org/r/20220308021200.9245-1-tung.q.nguyen@dektech.com.au
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 net/tipc/link.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/net/tipc/link.c b/net/tipc/link.c
index 4e7936d9b442..115a4a7950f5 100644
--- a/net/tipc/link.c
+++ b/net/tipc/link.c
@@ -2285,6 +2285,11 @@ static int tipc_link_proto_rcv(struct tipc_link *l, struct sk_buff *skb,
 		break;
 
 	case STATE_MSG:
+		/* Validate Gap ACK blocks, drop if invalid */
+		glen = tipc_get_gap_ack_blks(&ga, l, hdr, true);
+		if (glen > dlen)
+			break;
+
 		l->rcv_nxt_state = msg_seqno(hdr) + 1;
 
 		/* Update own tolerance if peer indicates a non-zero value */
@@ -2310,10 +2315,6 @@ static int tipc_link_proto_rcv(struct tipc_link *l, struct sk_buff *skb,
 			break;
 		}
 
-		/* Receive Gap ACK blocks from peer if any */
-		glen = tipc_get_gap_ack_blks(&ga, l, hdr, true);
-		if(glen > dlen)
-			break;
 		tipc_mon_rcv(l->net, data + glen, dlen - glen, l->addr,
 			     &l->mon_state, l->bearer_id);
 
-- 
2.34.1