netlink: handle errors from netlink_dump() (b44d211e) · Commits · 戴 / test

netlink_dump() may failed, but nobody handle its error. It generates output data, when a previous portion has been returned to user space. This mechanism works when all data isn't go in skb. If we enter in netlink_recvmsg() and skb is absent in the recv queue, the netlink_dump() will not been executed. So if netlink_dump() is failed one time, the new data never appear and the reader will sleep forever. netlink_dump() is called from two places: 1. from netlink_sendmsg->...->netlink_dump_start(). In this place we can report error directly and it will be returned by sendmsg(). 2. from netlink_recvmsg There we can't report error directly, because we have a portion of valid output data and call netlink_dump() for prepare the next portion. If netlink_dump() is failed, the socket will be mark as error and the next recvmsg will be failed. Signed-off-by:

Andrey Vagin <avagin@openvz.org> Signed-off-by:

David S. Miller <davem@davemloft.net>

net/netlink/af_netlink.c

+14 −4

Original line number	Diff line number	Diff line
		@@ -1407,7 +1407,7 @@ static int netlink_recvmsg(struct kiocb kiocb, struct socket sock,
		int noblock = flags&MSG_DONTWAIT;
		size_t copied;
		struct sk_buff skb, data_skb;
		int err;
		int err, ret;

		if (flags&MSG_OOB)
		return -EOPNOTSUPP;
		@@ -1470,8 +1470,13 @@ static int netlink_recvmsg(struct kiocb kiocb, struct socket sock,

		skb_free_datagram(sk, skb);

		if (nlk->cb && atomic_read(&sk->sk_rmem_alloc) <= sk->sk_rcvbuf / 2)
		netlink_dump(sk);
		if (nlk->cb && atomic_read(&sk->sk_rmem_alloc) <= sk->sk_rcvbuf / 2) {
		ret = netlink_dump(sk);
		if (ret) {
		sk->sk_err = ret;
		sk->sk_error_report(sk);
		}
		}

		scm_recv(sock, msg, siocb->scm, flags);
		out:
		@@ -1736,6 +1741,7 @@ int netlink_dump_start(struct sock ssk, struct sk_buff skb,
		struct netlink_callback *cb;
		struct sock *sk;
		struct netlink_sock *nlk;
		int ret;

		cb = kzalloc(sizeof(*cb), GFP_KERNEL);
		if (cb == NULL)
		@@ -1764,9 +1770,13 @@ int netlink_dump_start(struct sock ssk, struct sk_buff skb,
		nlk->cb = cb;
		mutex_unlock(nlk->cb_mutex);

		netlink_dump(sk);
		ret = netlink_dump(sk);

		sock_put(sk);

		if (ret)
		return ret;

		/* We successfully started a dump, by returning -EINTR we
		* signal not to send ACK even if it was requested.
		*/

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