netdev - [PATCH] dccp: CVE-2017-8824: use-after-free in DCCP code

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Message-ID: <5a25c77d.31a9df0a.42891.7c0f@mx.google.com>
Date:   Mon,  4 Dec 2017 23:08:37 +0100
From:   simo.ghannam@...il.com
To:     netdev@...r.kernel.org
Cc:     Mohamed Ghannam <simo.ghannam@...il.com>
Subject: [PATCH] dccp: CVE-2017-8824: use-after-free in DCCP code

From: Mohamed Ghannam <simo.ghannam@...il.com>

	Whenever the sock object is in DCCP_CLOSED state,
	dccp_disconnect() must free dccps_hc_tx_ccid and
	dccps_hc_rx_ccid and set to NULL.

Signed-off-by: Mohamed Ghannam <simo.ghannam@...il.com>
---
 net/dccp/proto.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/net/dccp/proto.c b/net/dccp/proto.c
index b68168f..9d43c1f 100644
--- a/net/dccp/proto.c
+++ b/net/dccp/proto.c
@@ -259,6 +259,7 @@ int dccp_disconnect(struct sock *sk, int flags)
 {
 	struct inet_connection_sock *icsk = inet_csk(sk);
 	struct inet_sock *inet = inet_sk(sk);
+	struct dccp_sock *dp = dccp_sk(sk);
 	int err = 0;
 	const int old_state = sk->sk_state;
 
@@ -278,6 +279,10 @@ int dccp_disconnect(struct sock *sk, int flags)
 		sk->sk_err = ECONNRESET;
 
 	dccp_clear_xmit_timers(sk);
+	ccid_hc_rx_delete(dp->dccps_hc_rx_ccid, sk);
+	ccid_hc_tx_delete(dp->dccps_hc_tx_ccid, sk);
+	dp->dccps_hc_rx_ccid = NULL;
+	dp->dccps_hc_tx_ccid = NULL;
 
 	__skb_queue_purge(&sk->sk_receive_queue);
 	__skb_queue_purge(&sk->sk_write_queue);
-- 
2.7.4