From b44d211e166b4b0dae8ce379f9d2e3ac164b5b60 Mon Sep 17 00:00:00 2001 From: Andrey Vagin Date: Mon, 21 Feb 2011 02:40:47 +0000 Subject: [PATCH] netlink: handle errors from netlink_dump() 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 Signed-off-by: David S. Miller --- net/netlink/af_netlink.c | 18 ++++++++++++++---- 1 file changed, 14 insertions(+), 4 deletions(-) diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c index 478181d53c55..1f924595bdef 100644 --- a/net/netlink/af_netlink.c +++ b/net/netlink/af_netlink.c @@ -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. */ -- 2.30.2