WSL2-Linux-Kernel/net/l2tp
Gong, Sishuai 69e16d01d1 net: fix a concurrency bug in l2tp_tunnel_register()
l2tp_tunnel_register() registers a tunnel without fully
initializing its attribute. This can allow another kernel thread
running l2tp_xmit_core() to access the uninitialized data and
then cause a kernel NULL pointer dereference error, as shown below.

Thread 1    Thread 2
//l2tp_tunnel_register()
list_add_rcu(&tunnel->list, &pn->l2tp_tunnel_list);
           //pppol2tp_connect()
           tunnel = l2tp_tunnel_get(sock_net(sk), info.tunnel_id);
           // Fetch the new tunnel
           ...
           //l2tp_xmit_core()
           struct sock *sk = tunnel->sock;
           ...
           bh_lock_sock(sk);
           //Null pointer error happens
tunnel->sock = sk;

Fix this bug by initializing tunnel->sock before adding the
tunnel into l2tp_tunnel_list.

Reviewed-by: Cong Wang <cong.wang@bytedance.com>
Signed-off-by: Sishuai Gong <sishuai@purdue.edu>
Reported-by: Sishuai Gong <sishuai@purdue.edu>
Signed-off-by: David S. Miller <davem@davemloft.net>
2021-04-27 14:23:13 -07:00
..
Kconfig treewide: replace '---help---' in Kconfig files with 'help' 2020-06-14 01:57:21 +09:00
Makefile l2tp: add tracepoint infrastructure to core 2020-08-22 12:44:37 -07:00
l2tp_core.c net: fix a concurrency bug in l2tp_tunnel_register() 2021-04-27 14:23:13 -07:00
l2tp_core.h net: l2tp: reduce log level of messages in receive path, add counter instead 2021-03-03 16:55:02 -08:00
l2tp_debugfs.c l2tp: remove tunnel and session debug flags field 2020-08-22 12:44:37 -07:00
l2tp_eth.c l2tp: remove header length param from l2tp_xmit_skb 2020-09-03 12:19:03 -07:00
l2tp_ip.c l2tp: make magic feather checks more useful 2020-09-03 12:19:03 -07:00
l2tp_ip6.c lsm,selinux: pass flowi_common instead of flowi to the LSM hooks 2020-11-23 18:36:21 -05:00
l2tp_netlink.c net: l2tp: reduce log level of messages in receive path, add counter instead 2021-03-03 16:55:02 -08:00
l2tp_ppp.c l2tp: make magic feather checks more useful 2020-09-03 12:19:03 -07:00
trace.h l2tp: add tracepoint definitions in trace.h 2020-08-22 12:44:37 -07:00