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Message-ID: <CANn89iKhWyw9YvS_cgfuym0sK4O-FS2xXyWgU=MjZ0g=wesYjg@mail.gmail.com>
Date: Wed, 17 Jan 2024 12:28:40 +0100
From: Eric Dumazet <edumazet@...gle.com>
To: Zhengchao Shao <shaozhengchao@...wei.com>
Cc: netdev@...r.kernel.org, davem@...emloft.net, kuba@...nel.org,
pabeni@...hat.com, dsahern@...nel.org, sming56@...yun.com,
weiyongjun1@...wei.com, yuehaibing@...wei.com
Subject: Re: [PATCH net,v3] tcp: make sure init the accept_queue's spinlocks once
On Wed, Jan 17, 2024 at 7:22 AM Zhengchao Shao <shaozhengchao@...wei.com> wrote:
>
> When I run syz's reproduction C program locally, it causes the following
> </TASK>
>
> The issue triggering process is analyzed as follows:
> Thread A Thread B
> tcp_v4_rcv //receive ack TCP packet inet_shutdown
> tcp_check_req tcp_disconnect //disconnect sock
> ... tcp_set_state(sk, TCP_CLOSE)
> inet_csk_complete_hashdance ...
> inet_csk_reqsk_queue_add inet_listen //start listen
> spin_lock(&queue->rskq_lock) inet_csk_listen_start
> ... reqsk_queue_alloc
> ... spin_lock_init
> spin_unlock(&queue->rskq_lock) //warning
>
> When the socket receives the ACK packet during the three-way handshake,
> it will hold spinlock. And then the user actively shutdowns the socket
> and listens to the socket immediately, the spinlock will be initialized.
> When the socket is going to release the spinlock, a warning is generated.
> Also the same issue to fastopenq.lock.
>
> Move init spinlock to inet_create and inet_accept to make sure init the
> accept_queue's spinlocks once.
>
> Fixes: fff1f3001cc5 ("tcp: add a spinlock to protect struct request_sock_queue")
> Fixes: 168a8f58059a ("tcp: TCP Fast Open Server - main code path")
> Reported-by: Ming Shu <sming56@...yun.com>
> Signed-off-by: Zhengchao Shao <shaozhengchao@...wei.com>
> ---
> v3: Move init spinlock to inet_create and inet_accept.
> v2: Add 'init_done' to make sure init the accept_queue's spinlocks once.
> ---
> net/core/request_sock.c | 3 ---
> net/ipv4/af_inet.c | 11 +++++++++++
> net/ipv4/inet_connection_sock.c | 8 ++++++++
> 3 files changed, 19 insertions(+), 3 deletions(-)
>
> diff --git a/net/core/request_sock.c b/net/core/request_sock.c
> index f35c2e998406..63de5c635842 100644
> --- a/net/core/request_sock.c
> +++ b/net/core/request_sock.c
> @@ -33,9 +33,6 @@
>
> void reqsk_queue_alloc(struct request_sock_queue *queue)
> {
> - spin_lock_init(&queue->rskq_lock);
> -
> - spin_lock_init(&queue->fastopenq.lock);
> queue->fastopenq.rskq_rst_head = NULL;
> queue->fastopenq.rskq_rst_tail = NULL;
> queue->fastopenq.qlen = 0;
> diff --git a/net/ipv4/af_inet.c b/net/ipv4/af_inet.c
> index 835f4f9d98d2..6589741157a4 100644
> --- a/net/ipv4/af_inet.c
> +++ b/net/ipv4/af_inet.c
> @@ -244,6 +244,14 @@ int inet_listen(struct socket *sock, int backlog)
> }
> EXPORT_SYMBOL(inet_listen);
>
> +static void __inet_init_csk_lock(struct sock *sk)
> +{
> + struct inet_connection_sock *icsk = inet_csk(sk);
> +
> + spin_lock_init(&icsk->icsk_accept_queue.rskq_lock);
> + spin_lock_init(&icsk->icsk_accept_queue.fastopenq.lock);
> +}
This probably could be an inline helper in a suitable include file.
No need for __prefix btw.
static void inline inet_init_csk_locks(struct sock *sk)
{
struct inet_connection_sock *icsk = inet_csk(sk);
spin_lock_init(&icsk->icsk_accept_queue.rskq_lock);
spin_lock_init(&icsk->icsk_accept_queue.fastopenq.lock);
}
> +
> /*
> * Create an inet socket.
> */
> @@ -330,6 +338,9 @@ static int inet_create(struct net *net, struct socket *sock, int protocol,
> if (INET_PROTOSW_REUSE & answer_flags)
> sk->sk_reuse = SK_CAN_REUSE;
>
> + if (INET_PROTOSW_ICSK & answer_flags)
> + __inet_init_csk_lock(sk);
> +
> inet = inet_sk(sk);
> inet_assign_bit(IS_ICSK, sk, INET_PROTOSW_ICSK & answer_flags);
>
> diff --git a/net/ipv4/inet_connection_sock.c b/net/ipv4/inet_connection_sock.c
> index 8e2eb1793685..5d3277ab9954 100644
> --- a/net/ipv4/inet_connection_sock.c
> +++ b/net/ipv4/inet_connection_sock.c
> @@ -655,6 +655,7 @@ struct sock *inet_csk_accept(struct sock *sk, int flags, int *err, bool kern)
> {
> struct inet_connection_sock *icsk = inet_csk(sk);
> struct request_sock_queue *queue = &icsk->icsk_accept_queue;
> + struct request_sock_queue *newqueue;
> struct request_sock *req;
> struct sock *newsk;
> int error;
> @@ -727,6 +728,13 @@ struct sock *inet_csk_accept(struct sock *sk, int flags, int *err, bool kern)
> }
> if (req)
> reqsk_put(req);
> +
> + if (newsk) {
> + newqueue = &inet_csk(newsk)->icsk_accept_queue;
> + spin_lock_init(&newqueue->rskq_lock);
> + spin_lock_init(&newqueue->fastopenq.lock);
> + }
So that we could here use a common helper
if (newsk)
inet_init_csk_locks(newsk);
Thanks, this is looking quite nice.
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