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authorTetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>2020-09-02 22:44:16 +0900
committerDavid S. Miller <davem@davemloft.net>2020-09-02 15:49:30 -0700
commit2a63866c8b51a3f72cea388dfac259d0e14c4ba6 (patch)
tree1832fe4454c8447abac9bf1e542c157dd643faa0 /net/tipc
parent05d4487197b2b71d5363623c28924fd58c71c0b6 (diff)
tipc: fix shutdown() of connectionless socket
syzbot is reporting hung task at nbd_ioctl() [1], for there are two problems regarding TIPC's connectionless socket's shutdown() operation. ---------- #include <fcntl.h> #include <sys/socket.h> #include <sys/ioctl.h> #include <linux/nbd.h> #include <unistd.h> int main(int argc, char *argv[]) { const int fd = open("/dev/nbd0", 3); alarm(5); ioctl(fd, NBD_SET_SOCK, socket(PF_TIPC, SOCK_DGRAM, 0)); ioctl(fd, NBD_DO_IT, 0); /* To be interrupted by SIGALRM. */ 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> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/tipc')
-rw-r--r--net/tipc/socket.c9
1 files changed, 6 insertions, 3 deletions
diff --git a/net/tipc/socket.c b/net/tipc/socket.c
index 07419f36116a..d49c6173954a 100644
--- a/net/tipc/socket.c
+++ b/net/tipc/socket.c
@@ -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;