diff options
| author | Ka-Cheong Poon <ka-cheong.poon@oracle.com> | 2018-03-01 21:07:18 -0800 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2018-03-02 09:40:27 -0500 |
| commit | 84eef2b2187ed73c0e4520cbfeb874e964a0b56a (patch) | |
| tree | 910036b61425b56e91761802c77dc2ea15357b2a /net | |
| parent | a5f7b0eeb219620e1f7388db817e2fb584c00b64 (diff) | |
| download | linux-84eef2b2187ed73c0e4520cbfeb874e964a0b56a.tar.bz2 | |
rds: Incorrect reference counting in TCP socket creation
Commit 0933a578cd55 ("rds: tcp: use sock_create_lite() to create the
accept socket") has a reference counting issue in TCP socket creation
when accepting a new connection. The code uses sock_create_lite() to
create a kernel socket. But it does not do __module_get() on the
socket owner. When the connection is shutdown and sock_release() is
called to free the socket, the owner's reference count is decremented
and becomes incorrect. Note that this bug only shows up when the socket
owner is configured as a kernel module.
v2: Update comments
Fixes: 0933a578cd55 ("rds: tcp: use sock_create_lite() to create the accept socket")
Signed-off-by: Ka-Cheong Poon <ka-cheong.poon@oracle.com>
Acked-by: Santosh Shilimkar <santosh.shilimkar@oracle.com>
Acked-by: Sowmini Varadhan <sowmini.varadhan@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net')
| -rw-r--r-- | net/rds/tcp_listen.c | 14 |
1 files changed, 11 insertions, 3 deletions
diff --git a/net/rds/tcp_listen.c b/net/rds/tcp_listen.c index c061d6eb465d..22571189f21e 100644 --- a/net/rds/tcp_listen.c +++ b/net/rds/tcp_listen.c @@ -1,5 +1,5 @@ /* - * Copyright (c) 2006 Oracle. All rights reserved. + * Copyright (c) 2006, 2018 Oracle. All rights reserved. * * This software is available to you under a choice of one of two * licenses. You may choose to be licensed under the terms of the GNU @@ -142,12 +142,20 @@ int rds_tcp_accept_one(struct socket *sock) if (ret) goto out; - new_sock->type = sock->type; - new_sock->ops = sock->ops; ret = sock->ops->accept(sock, new_sock, O_NONBLOCK, true); if (ret < 0) goto out; + /* sock_create_lite() does not get a hold on the owner module so we + * need to do it here. Note that sock_release() uses sock->ops to + * determine if it needs to decrement the reference count. So set + * sock->ops after calling accept() in case that fails. And there's + * no need to do try_module_get() as the listener should have a hold + * already. + */ + new_sock->ops = sock->ops; + __module_get(new_sock->ops->owner); + ret = rds_tcp_keepalive(new_sock); if (ret < 0) goto out; |