From: Tan Hu tan.hu@zte.com.cn
[ Upstream commit a53b42c11815d2357e31a9403ae3950517525894 ]
We came across infinite loop in ipvs when using ipvs in docker env.
When ipvs receives new packets and cannot find an ipvs connection, it will create a new connection, then if the dest is unavailable (i.e. IP_VS_DEST_F_AVAILABLE), the packet will be dropped sliently.
But if the dropped packet is the first packet of this connection, the connection control timer never has a chance to start and the ipvs connection cannot be released. This will lead to memory leak, or infinite loop in cleanup_net() when net namespace is released like this:
ip_vs_conn_net_cleanup at ffffffffa0a9f31a [ip_vs] __ip_vs_cleanup at ffffffffa0a9f60a [ip_vs] ops_exit_list at ffffffff81567a49 cleanup_net at ffffffff81568b40 process_one_work at ffffffff810a851b worker_thread at ffffffff810a9356 kthread at ffffffff810b0b6f ret_from_fork at ffffffff81697a18
race condition: CPU1 CPU2 ip_vs_in() ip_vs_conn_new() ip_vs_del_dest() __ip_vs_unlink_dest() ~IP_VS_DEST_F_AVAILABLE cp->dest && !IP_VS_DEST_F_AVAILABLE __ip_vs_conn_put ... cleanup_net ---> infinite looping
Fix this by checking whether the timer already started.
Signed-off-by: Tan Hu tan.hu@zte.com.cn Reviewed-by: Jiang Biao jiang.biao2@zte.com.cn Acked-by: Julian Anastasov ja@ssi.bg Acked-by: Simon Horman horms@verge.net.au Signed-off-by: Pablo Neira Ayuso pablo@netfilter.org Signed-off-by: Sasha Levin alexander.levin@microsoft.com --- net/netfilter/ipvs/ip_vs_core.c | 15 +++++++++++---- 1 file changed, 11 insertions(+), 4 deletions(-)
diff --git a/net/netfilter/ipvs/ip_vs_core.c b/net/netfilter/ipvs/ip_vs_core.c index 5cb7cac9177d..1bd53b1e7672 100644 --- a/net/netfilter/ipvs/ip_vs_core.c +++ b/net/netfilter/ipvs/ip_vs_core.c @@ -1960,13 +1960,20 @@ ip_vs_in(struct netns_ipvs *ipvs, unsigned int hooknum, struct sk_buff *skb, int if (cp->dest && !(cp->dest->flags & IP_VS_DEST_F_AVAILABLE)) { /* the destination server is not available */
- if (sysctl_expire_nodest_conn(ipvs)) { + __u32 flags = cp->flags; + + /* when timer already started, silently drop the packet.*/ + if (timer_pending(&cp->timer)) + __ip_vs_conn_put(cp); + else + ip_vs_conn_put(cp); + + if (sysctl_expire_nodest_conn(ipvs) && + !(flags & IP_VS_CONN_F_ONE_PACKET)) { /* try to expire the connection immediately */ ip_vs_conn_expire_now(cp); } - /* don't restart its timer, and silently - drop the packet. */ - __ip_vs_conn_put(cp); + return NF_DROP; }