From b65eebc6e33ad2a8ee77a59b8931c407d41be9e2 Mon Sep 17 00:00:00 2001 From: Duoming Zhou <duoming@zju.edu.cn> Date: Fri, 22 Apr 2022 13:01:24 +0000 Subject: [PATCH] ax25: fix NPD bug in ax25_disconnect mainline inclusion from mainline-v5.17-rc4 commit 7ec02f5ac8a5be5a3f20611731243dc5e1d9ba10 category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/I53VJO CVE: CVE-2022-1199 -------------------------------- The ax25_disconnect() in ax25_kill_by_device() is not protected by any locks, thus there is a race condition between ax25_disconnect() and ax25_destroy_socket(). when ax25->sk is assigned as NULL by ax25_destroy_socket(), a NULL pointer dereference bug will occur if site (1) or (2) dereferences ax25->sk. ax25_kill_by_device() | ax25_release() ax25_disconnect() | ax25_destroy_socket() ... | if(ax25->sk != NULL) | ... ... | ax25->sk = NULL; bh_lock_sock(ax25->sk); //(1) | ... ... | bh_unlock_sock(ax25->sk); //(2)| This patch moves ax25_disconnect() into lock_sock(), which can synchronize with ax25_destroy_socket() in ax25_release(). Fail log: =============================================================== BUG: kernel NULL pointer dereference, address: 0000000000000088 ... RIP: 0010:_raw_spin_lock+0x7e/0xd0 ... Call Trace: ax25_disconnect+0xf6/0x220 ax25_device_event+0x187/0x250 raw_notifier_call_chain+0x5e/0x70 dev_close_many+0x17d/0x230 rollback_registered_many+0x1f1/0x950 unregister_netdevice_queue+0x133/0x200 unregister_netdev+0x13/0x20 ... Signed-off-by: Duoming Zhou <duoming@zju.edu.cn> Signed-off-by: David S. Miller <davem@davemloft.net> Conflict: net/ax25/af_ax25.c Signed-off-by: Zhengchao Shao <shaozhengchao@huawei.com> Reviewed-by: Wei Yongjun <weiyongjun1@huawei.com> Reviewed-by: Xiu Jianfeng <xiujianfeng@huawei.com> Signed-off-by: Yongqiang Liu <liuyongqiang13@huawei.com> --- net/ax25/af_ax25.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/net/ax25/af_ax25.c b/net/ax25/af_ax25.c index 37a333d0ee03..3a5812c1a098 100644 --- a/net/ax25/af_ax25.c +++ b/net/ax25/af_ax25.c @@ -101,8 +101,8 @@ static void ax25_kill_by_device(struct net_device *dev) spin_unlock_bh(&ax25_list_lock); lock_sock(sk); s->ax25_dev = NULL; - release_sock(sk); ax25_disconnect(s, ENETUNREACH); + release_sock(sk); spin_lock_bh(&ax25_list_lock); sock_put(sk); /* The entry could have been deleted from the -- GitLab