From: Mao Wenan maowenan@huawei.com
After the commit c4e97b06cfdc ("net: rds: force to destroy connection if t_sock is NULL in rds_tcp_kill_sock()."), it introduced null-ptr-deref in rds_tcp_kill_sock as below:
BUG: KASAN: null-ptr-deref on address 0000000000000020 Read of size 8 by task kworker/u16:10/910 CPU: 3 PID: 910 Comm: kworker/u16:10 Not tainted 4.4.178+ #3 Hardware name: linux,dummy-virt (DT) Workqueue: netns cleanup_net Call trace: [<ffffff90080abb50>] dump_backtrace+0x0/0x618 [<ffffff90080ac1a0>] show_stack+0x38/0x60 [<ffffff9008c42b78>] dump_stack+0x1a8/0x230 [<ffffff90085d469c>] kasan_report_error+0xc8c/0xfc0 [<ffffff90085d54a4>] kasan_report+0x94/0xd8 [<ffffff90085d1b28>] __asan_load8+0x88/0x150 [<ffffff9009c9cc2c>] rds_tcp_dev_event+0x734/0xb48 [<ffffff90081eacb0>] raw_notifier_call_chain+0x150/0x1e8 [<ffffff900973fec0>] call_netdevice_notifiers_info+0x90/0x110 [<ffffff9009764874>] netdev_run_todo+0x2f4/0xb08 [<ffffff9009796d34>] rtnl_unlock+0x2c/0x48 [<ffffff9009756484>] default_device_exit_batch+0x444/0x528 [<ffffff9009720498>] ops_exit_list+0x1c0/0x240 [<ffffff9009724a80>] cleanup_net+0x738/0xbf8 [<ffffff90081ca6cc>] process_one_work+0x96c/0x13e0 [<ffffff90081cf370>] worker_thread+0x7e0/0x1910 [<ffffff90081e7174>] kthread+0x304/0x390 [<ffffff9008094280>] ret_from_fork+0x10/0x50
If the first loop add the tc->t_sock = NULL to the tmp_list, 1). list_for_each_entry_safe(tc, _tc, &rds_tcp_conn_list, t_tcp_node)
then the second loop is to find connections to destroy, tc->t_sock might equal NULL, and tc->t_sock->sk happens null-ptr-deref. 2). list_for_each_entry_safe(tc, _tc, &tmp_list, t_tcp_node)
Fixes: c4e97b06cfdc ("net: rds: force to destroy connection if t_sock is NULL in rds_tcp_kill_sock().") Signed-off-by: Mao Wenan maowenan@huawei.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- net/rds/tcp.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-)
--- a/net/rds/tcp.c +++ b/net/rds/tcp.c @@ -352,9 +352,11 @@ static void rds_tcp_kill_sock(struct net } spin_unlock_irq(&rds_tcp_conn_lock); list_for_each_entry_safe(tc, _tc, &tmp_list, t_tcp_node) { - sk = tc->t_sock->sk; - sk->sk_prot->disconnect(sk, 0); - tcp_done(sk); + if (tc->t_sock) { + sk = tc->t_sock->sk; + sk->sk_prot->disconnect(sk, 0); + tcp_done(sk); + } if (tc->conn->c_passive) rds_conn_destroy(tc->conn->c_passive); rds_conn_destroy(tc->conn);