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mptcp: fix locking for setsockopt corner-case

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[ Upstream commit 21e43569685de4ad773fb060c11a15f3fd5e7ac4 ]

We need to call the __mptcp_nmpc_socket(), and later subflow socket
access under the msk socket lock, or e.g. a racing connect() could
change the socket status under the hood, with unexpected results.

Fixes: 54635bd04701 ("mptcp: add TCP_FASTOPEN_CONNECT socket option")
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Paolo Abeni 2023-02-07 14:04:14 +01:00 committed by Greg Kroah-Hartman
parent 94ed108bf1
commit 03edc4a27d
1 changed files with 9 additions and 2 deletions
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11
net/mptcp/sockopt.c
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@ -772,14 +772,21 @@ static int mptcp_setsockopt_sol_tcp_defer(struct mptcp_sock *msk, sockptr_t optv
static int mptcp_setsockopt_first_sf_only(struct mptcp_sock *msk, int level, int optname,
sockptr_t optval, unsigned int optlen)
{
struct sock *sk = (struct sock *)msk;
struct socket *sock;
int ret = -EINVAL;
/* Limit to first subflow, before the connection establishment */
lock_sock(sk);
sock = __mptcp_nmpc_socket(msk);
if (!sock)
return -EINVAL;
goto unlock;
return tcp_setsockopt(sock->sk, level, optname, optval, optlen);
ret = tcp_setsockopt(sock->sk, level, optname, optval, optlen);
unlock:
release_sock(sk);
return ret;
}
static int mptcp_setsockopt_sol_tcp(struct mptcp_sock *msk, int optname,