Messages in this thread Patch in this message | | | From | Qingjie Xing <> | Subject | [PATCH] netlink: Fix the netlink socket malfunction due to concurrency | Date | Fri, 18 Aug 2023 11:37:11 -0700 |
| |
The concurrent Invocation of netlink_attachskb() and netlink_recvmsg() on different CPUs causes malfunction of netlink socket.
The concurrent scenario of netlink_recvmsg() and netlink_attachskb() as following:
CPU A CPU B ======== ======== netlink_recvmsg() netlink_attachskb() [1]bit NETLINK_S_CONGESTED is set netlink_overrun() netlink_rcv_wake() [2]sk_receive_queue is empty clear bit NETLINK_S_CONGESTED [3]NETLINK_F_RECV_NO_ENOBUFS not set set bit NETLINK_S_CONGESTED
In this scenario, the socket's receive queue is empty. Additionally, due to the NETLINK_S_CONGESTED flag being set, all packets sent to this socket are discarded.
To prevent this situation, we need to introduce a check for whether the socket receive buffer is full before setting the NETLINK_S_CONGESTED flag.
Signed-off-by: Qingjie Xing <xqjcool@gmail.com> --- net/netlink/af_netlink.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c index 383631873748..80bcce9acbfc 100644 --- a/net/netlink/af_netlink.c +++ b/net/netlink/af_netlink.c @@ -352,7 +352,8 @@ static void netlink_overrun(struct sock *sk) struct netlink_sock *nlk = nlk_sk(sk); if (!(nlk->flags & NETLINK_F_RECV_NO_ENOBUFS)) { - if (!test_and_set_bit(NETLINK_S_CONGESTED, + if (atomic_read(&sk->sk_rmem_alloc) > sk->sk_rcvbuf + && !test_and_set_bit(NETLINK_S_CONGESTED, &nlk_sk(sk)->state)) { sk->sk_err = ENOBUFS; sk_error_report(sk); -- 2.41.0
| |