@@ -2771,18 +2771,21 @@ static int tipc_shutdown(struct socket *sock, int how)
trace_tipc_sk_shutdown(sk, NULL, TIPC_DUMP_ALL, " ");
__tipc_shutdown(sock, TIPC_CONN_SHUTDOWN);
- sk->sk_shutdown = SEND_SHUTDOWN;
+ if (tipc_sk_type_connectionless(sk))
+ sk->sk_shutdown = SHUTDOWN_MASK;
+ else
+ sk->sk_shutdown = SEND_SHUTDOWN;
if (sk->sk_state == TIPC_DISCONNECTING) {
/* Discard any unreceived messages */
__skb_queue_purge(&sk->sk_receive_queue);
- /* Wake up anyone sleeping in poll */
- sk->sk_state_change(sk);
res = 0;
} else {
res = -ENOTCONN;
}
+ /* Wake up anyone sleeping in poll. */
+ sk->sk_state_change(sk);
release_sock(sk);
return res;
syzbot is reporting hung task at nbd_ioctl() [1], for there are two problems regarding TIPC's connectionless socket's shutdown() operation. I found C reproducer for this problem (shown below) from "no output from test machine (2)" report. ---------- int main(int argc, char *argv[]) { const int fd = open("/dev/nbd0", 3); ioctl(fd, NBD_SET_SOCK, socket(PF_TIPC, SOCK_DGRAM, 0)); ioctl(fd, NBD_DO_IT, 0); return 0; } ---------- One problem is that wait_for_completion() from flush_workqueue() from nbd_start_device_ioctl() from nbd_ioctl() cannot be completed when nbd_start_device_ioctl() received a signal at wait_event_interruptible(), for tipc_shutdown() from kernel_sock_shutdown(SHUT_RDWR) from nbd_mark_nsock_dead() from sock_shutdown() from nbd_start_device_ioctl() is failing to wake up a WQ thread sleeping at wait_woken() from tipc_wait_for_rcvmsg() from sock_recvmsg() from sock_xmit() from nbd_read_stat() from recv_work() scheduled by nbd_start_device() from nbd_start_device_ioctl(). Fix this problem by always invoking sk->sk_state_change() (like inet_shutdown() does) when tipc_shutdown() is called. The other problem is that tipc_wait_for_rcvmsg() cannot return when tipc_shutdown() is called, for tipc_shutdown() sets sk->sk_shutdown to SEND_SHUTDOWN (despite "how" is SHUT_RDWR) while tipc_wait_for_rcvmsg() needs sk->sk_shutdown set to RCV_SHUTDOWN or SHUTDOWN_MASK. Fix this problem by setting sk->sk_shutdown to SHUTDOWN_MASK (like inet_shutdown() does) when the socket is connectionless. [1] https://syzkaller.appspot.com/bug?id=3fe51d307c1f0a845485cf1798aa059d12bf18b2 Reported-by: syzbot <syzbot+e36f41d207137b5d12f7@syzkaller.appspotmail.com> Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> --- net/tipc/socket.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-)