linux-kernel - [PATCH 5.18 092/231] mptcp: fix subflow traversal at disconnect time

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Date:   Tue, 19 Jul 2022 13:52:57 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, van fantasy <g1042620637@...il.com>,
        Matthieu Baerts <matthieu.baerts@...sares.net>,
        Mat Martineau <mathew.j.martineau@...ux.intel.com>,
        Paolo Abeni <pabeni@...hat.com>,
        "David S. Miller" <davem@...emloft.net>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.18 092/231] mptcp: fix subflow traversal at disconnect time

From: Paolo Abeni <pabeni@...hat.com>

[ Upstream commit 5c835bb142d4013c2ab24bff5ae9f6709a39cbcf ]

At disconnect time the MPTCP protocol traverse the subflows
list closing each of them. In some circumstances - MPJ subflow,
passive MPTCP socket, the latter operation can remove the
subflow from the list, invalidating the current iterator.

Address the issue using the safe list traversing helper
variant.

Reported-by: van fantasy <g1042620637@...il.com>
Fixes: b29fcfb54cd7 ("mptcp: full disconnect implementation")
Tested-by: Matthieu Baerts <matthieu.baerts@...sares.net>
Reviewed-by: Mat Martineau <mathew.j.martineau@...ux.intel.com>
Signed-off-by: Paolo Abeni <pabeni@...hat.com>
Signed-off-by: Mat Martineau <mathew.j.martineau@...ux.intel.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 net/mptcp/protocol.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -2840,12 +2840,12 @@ static void mptcp_copy_inaddrs(struct so
 
 static int mptcp_disconnect(struct sock *sk, int flags)
 {
-	struct mptcp_subflow_context *subflow;
+	struct mptcp_subflow_context *subflow, *tmp;
 	struct mptcp_sock *msk = mptcp_sk(sk);
 
 	inet_sk_state_store(sk, TCP_CLOSE);
 
-	mptcp_for_each_subflow(msk, subflow) {
+	list_for_each_entry_safe(subflow, tmp, &msk->conn_list, node) {
 		struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
 
 		__mptcp_close_ssk(sk, ssk, subflow, MPTCP_CF_FASTCLOSE);