From: Wang Hai <wanghai38@xxxxxxxxxx>
Date: Tue, 28 Sep 2021 11:14:39 +0800
> When use-gss-proxy is set to 1, write_gssp() creates a rpc client in
> gssp_rpc_create(), this increases netns refcount by 2, these refcounts
> are supposed to be released in rpcsec_gss_exit_net(), but it will never
> happen because rpcsec_gss_exit_net() is triggered only when netns
> refcount gets to 0, specifically:
> refcount=0 -> cleanup_net() -> ops_exit_list -> rpcsec_gss_exit_net
> It is a deadlock situation here, refcount will never get to 0 unless
> rpcsec_gss_exit_net() is called. So, in this case, the netns refcount
> should not be increased.
>
> In this case, kernel_connect()->unix_stream_connect() will take a netns
> refcount. According to commit 26abe14379f8 ("net: Modify sk_alloc to not
> reference count the netns of kernel sockets."), kernel sockets should not
> take the netns refcount, so unix_stream_connect() should not take
> the netns refcount when the sock is a kernel socket either.
>
> Signed-off-by: Wang Hai <wanghai38@xxxxxxxxxx>
> ---
> net/unix/af_unix.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
> index 92345c9bb60c..af6ba67779c8 100644
> --- a/net/unix/af_unix.c
> +++ b/net/unix/af_unix.c
> @@ -1317,7 +1317,8 @@ static int unix_stream_connect(struct socket *sock, struct sockaddr *uaddr,
> err = -ENOMEM;
>
> /* create new sock for complete connection */
> - newsk = unix_create1(sock_net(sk), NULL, 0, sock->type);
> + newsk = unix_create1(sock_net(sk), NULL,
> + !sk->sk_net_refcnt, sock->type);
This patch conflicts with the commit f4bd73b5a950 for now.
https://git.kernel.org/pub/scm/linux/kernel/git/netdev/net.git/commit/?id=f4bd73b5a950
Could you please rebase and resend the patch set?
> if (newsk == NULL)
> goto out;
>
> --
> 2.17.1
