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mptcp: add annotations around sk->sk_shutdown accesses

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Christoph reported the mptcp variant of a recently addressed plain
TCP issue. Similar to commit e14cadfd80d7 ("tcp: add annotations around
sk->sk_shutdown accesses") add READ/WRITE ONCE annotations to silence
KCSAN reports around lockless sk_shutdown access.

Fixes: 71ba088ce0aa ("mptcp: cleanup accept and poll")
Reported-by: Christoph Paasch <cpaasch@apple.com>
Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/401
Reviewed-by: Mat Martineau <martineau@kernel.org>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Mat Martineau <martineau@kernel.org>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Paolo Abeni 2023-05-31 12:37:07 -07:00 committed by Jakub Kicinski
parent 1b1b43ee7a
commit 6b9831bfd9
1 changed files with 16 additions and 13 deletions
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29
net/mptcp/protocol.c
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@ -603,7 +603,7 @@ static bool mptcp_check_data_fin(struct sock *sk)
WRITE_ONCE(msk->ack_seq, msk->ack_seq + 1);
WRITE_ONCE(msk->rcv_data_fin, 0);
sk->sk_shutdown |= RCV_SHUTDOWN;
WRITE_ONCE(sk->sk_shutdown, sk->sk_shutdown | RCV_SHUTDOWN);
smp_mb__before_atomic(); /* SHUTDOWN must be visible first */
switch (sk->sk_state) {
@ -910,7 +910,7 @@ static void mptcp_check_for_eof(struct mptcp_sock *msk)
/* hopefully temporary hack: propagate shutdown status
* to msk, when all subflows agree on it
*/
sk->sk_shutdown |= RCV_SHUTDOWN;
WRITE_ONCE(sk->sk_shutdown, sk->sk_shutdown | RCV_SHUTDOWN);
smp_mb__before_atomic(); /* SHUTDOWN must be visible first */
sk->sk_data_ready(sk);
@ -2526,7 +2526,7 @@ static void mptcp_check_fastclose(struct mptcp_sock *msk)
}
inet_sk_state_store(sk, TCP_CLOSE);
sk->sk_shutdown = SHUTDOWN_MASK;
WRITE_ONCE(sk->sk_shutdown, SHUTDOWN_MASK);
smp_mb__before_atomic(); /* SHUTDOWN must be visible first */
set_bit(MPTCP_WORK_CLOSE_SUBFLOW, &msk->flags);
@ -2958,7 +2958,7 @@ bool __mptcp_close(struct sock *sk, long timeout)
bool do_cancel_work = false;
int subflows_alive = 0;
sk->sk_shutdown = SHUTDOWN_MASK;
WRITE_ONCE(sk->sk_shutdown, SHUTDOWN_MASK);
if ((1 << sk->sk_state) & (TCPF_LISTEN | TCPF_CLOSE)) {
mptcp_listen_inuse_dec(sk);
@ -3101,7 +3101,7 @@ static int mptcp_disconnect(struct sock *sk, int flags)
mptcp_pm_data_reset(msk);
mptcp_ca_reset(sk);
sk->sk_shutdown = 0;
WRITE_ONCE(sk->sk_shutdown, 0);
sk_error_report(sk);
return 0;
}
@ -3806,9 +3806,6 @@ static __poll_t mptcp_check_writeable(struct mptcp_sock *msk)
{
struct sock *sk = (struct sock *)msk;
if (unlikely(sk->sk_shutdown & SEND_SHUTDOWN))
return EPOLLOUT | EPOLLWRNORM;
if (sk_stream_is_writeable(sk))
return EPOLLOUT | EPOLLWRNORM;
@ -3826,6 +3823,7 @@ static __poll_t mptcp_poll(struct file *file, struct socket *sock,
struct sock *sk = sock->sk;
struct mptcp_sock *msk;
__poll_t mask = 0;
u8 shutdown;
int state;
msk = mptcp_sk(sk);
@ -3842,17 +3840,22 @@ static __poll_t mptcp_poll(struct file *file, struct socket *sock,
return inet_csk_listen_poll(ssock->sk);
}
shutdown = READ_ONCE(sk->sk_shutdown);
if (shutdown == SHUTDOWN_MASK || state == TCP_CLOSE)
mask |= EPOLLHUP;
if (shutdown & RCV_SHUTDOWN)
mask |= EPOLLIN | EPOLLRDNORM | EPOLLRDHUP;
if (state != TCP_SYN_SENT && state != TCP_SYN_RECV) {
mask |= mptcp_check_readable(msk);
mask |= mptcp_check_writeable(msk);
if (shutdown & SEND_SHUTDOWN)
mask |= EPOLLOUT | EPOLLWRNORM;
else
mask |= mptcp_check_writeable(msk);
} else if (state == TCP_SYN_SENT && inet_sk(sk)->defer_connect) {
/* cf tcp_poll() note about TFO */
mask |= EPOLLOUT | EPOLLWRNORM;
}
if (sk->sk_shutdown == SHUTDOWN_MASK || state == TCP_CLOSE)
mask |= EPOLLHUP;
if (sk->sk_shutdown & RCV_SHUTDOWN)
mask |= EPOLLIN | EPOLLRDNORM | EPOLLRDHUP;
/* This barrier is coupled with smp_wmb() in __mptcp_error_report() */
smp_rmb();