diff options
| author | Paolo Abeni <pabeni@redhat.com> | 2023-05-31 12:37:04 -0700 |
|---|---|---|
| committer | Jakub Kicinski <kuba@kernel.org> | 2023-06-01 10:04:04 -0700 |
| commit | 5b825727d0871b23e8867f6371183e61628b4a26 (patch) | |
| tree | fe025fd4cdf1bbbbe5f889f759c00654b863d214 | |
| parent | 786fc12457268cc9b555dde6c22ae7300d4b40e1 (diff) | |
mptcp: add annotations around msk->subflow accesses
The MPTCP can access the first subflow socket in a few spots
outside the socket lock scope. That is actually safe, as MPTCP
will delete the socket itself only after the msk sock close().
Still the such accesses causes a few KCSAN splats, as reported
by Christoph. Silence the harmless warning adding a few annotation
around the relevant accesses.
Fixes: 71ba088ce0aa ("mptcp: cleanup accept and poll")
Reported-by: Christoph Paasch <cpaasch@apple.com>
Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/402
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>
| -rw-r--r-- | net/mptcp/protocol.c | 18 | ||||
| -rw-r--r-- | net/mptcp/protocol.h | 6 |
2 files changed, 15 insertions, 9 deletions
diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c index 9cafd3b89908..ce9de2c946b0 100644 --- a/net/mptcp/protocol.c +++ b/net/mptcp/protocol.c @@ -91,7 +91,7 @@ static int __mptcp_socket_create(struct mptcp_sock *msk) return err; msk->first = ssock->sk; - msk->subflow = ssock; + WRITE_ONCE(msk->subflow, ssock); subflow = mptcp_subflow_ctx(ssock->sk); list_add(&subflow->node, &msk->conn_list); sock_hold(ssock->sk); @@ -2282,7 +2282,7 @@ static void mptcp_dispose_initial_subflow(struct mptcp_sock *msk) { if (msk->subflow) { iput(SOCK_INODE(msk->subflow)); - msk->subflow = NULL; + WRITE_ONCE(msk->subflow, NULL); } } @@ -3136,7 +3136,7 @@ struct sock *mptcp_sk_clone(const struct sock *sk, msk = mptcp_sk(nsk); msk->local_key = subflow_req->local_key; msk->token = subflow_req->token; - msk->subflow = NULL; + WRITE_ONCE(msk->subflow, NULL); msk->in_accept_queue = 1; WRITE_ONCE(msk->fully_established, false); if (mp_opt->suboptions & OPTION_MPTCP_CSUMREQD) @@ -3184,7 +3184,7 @@ static struct sock *mptcp_accept(struct sock *sk, int flags, int *err, struct socket *listener; struct sock *newsk; - listener = msk->subflow; + listener = READ_ONCE(msk->subflow); if (WARN_ON_ONCE(!listener)) { *err = -EINVAL; return NULL; @@ -3736,10 +3736,10 @@ static int mptcp_stream_accept(struct socket *sock, struct socket *newsock, pr_debug("msk=%p", msk); - /* buggy applications can call accept on socket states other then LISTEN + /* Buggy applications can call accept on socket states other then LISTEN * but no need to allocate the first subflow just to error out. */ - ssock = msk->subflow; + ssock = READ_ONCE(msk->subflow); if (!ssock) return -EINVAL; @@ -3813,10 +3813,12 @@ static __poll_t mptcp_poll(struct file *file, struct socket *sock, state = inet_sk_state_load(sk); pr_debug("msk=%p state=%d flags=%lx", msk, state, msk->flags); if (state == TCP_LISTEN) { - if (WARN_ON_ONCE(!msk->subflow || !msk->subflow->sk)) + struct socket *ssock = READ_ONCE(msk->subflow); + + if (WARN_ON_ONCE(!ssock || !ssock->sk)) return 0; - return inet_csk_listen_poll(msk->subflow->sk); + return inet_csk_listen_poll(ssock->sk); } if (state != TCP_SYN_SENT && state != TCP_SYN_RECV) { diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h index de4667dafe59..7a1a3c35470f 100644 --- a/net/mptcp/protocol.h +++ b/net/mptcp/protocol.h @@ -305,7 +305,11 @@ struct mptcp_sock { struct list_head rtx_queue; struct mptcp_data_frag *first_pending; struct list_head join_list; - struct socket *subflow; /* outgoing connect/listener/!mp_capable */ + struct socket *subflow; /* outgoing connect/listener/!mp_capable + * The mptcp ops can safely dereference, using suitable + * ONCE annotation, the subflow outside the socket + * lock as such sock is freed after close(). + */ struct sock *first; struct mptcp_pm_data pm; struct { |