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authorLin Ma <linma@zju.edu.cn>2021-12-17 10:29:41 +0800
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2021-12-29 12:23:38 +0100
commitdf8f79bcc2e431bb6e1f0a8202cd2b06fd429889 (patch)
treefa7af995a6fa3861fe1f742775dea837445ac5a8 /net/ax25
parent0333eaf38500caa05c5c81de14a13328d0544f3c (diff)
ax25: NPD bug when detaching AX25 device
commit 1ade48d0c27d5da1ccf4b583d8c5fc8b534a3ac8 upstream. The existing cleanup routine implementation is not well synchronized with the syscall routine. When a device is detaching, below race could occur. static int ax25_sendmsg(...) { ... lock_sock() ax25 = sk_to_ax25(sk); if (ax25->ax25_dev == NULL) // CHECK ... ax25_queue_xmit(skb, ax25->ax25_dev->dev); // USE ... } static void ax25_kill_by_device(...) { ... if (s->ax25_dev == ax25_dev) { s->ax25_dev = NULL; ... } Other syscall functions like ax25_getsockopt, ax25_getname, ax25_info_show also suffer from similar races. To fix them, this patch introduce lock_sock() into ax25_kill_by_device in order to guarantee that the nullify action in cleanup routine cannot proceed when another socket request is pending. Signed-off-by: Hanjie Wu <nagi@zju.edu.cn> Signed-off-by: Lin Ma <linma@zju.edu.cn> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'net/ax25')
-rw-r--r--net/ax25/af_ax25.c4
1 files changed, 3 insertions, 1 deletions
diff --git a/net/ax25/af_ax25.c b/net/ax25/af_ax25.c
index 2fdb1b573e8c..1f84d41e22c3 100644
--- a/net/ax25/af_ax25.c
+++ b/net/ax25/af_ax25.c
@@ -85,8 +85,10 @@ static void ax25_kill_by_device(struct net_device *dev)
again:
ax25_for_each(s, &ax25_list) {
if (s->ax25_dev == ax25_dev) {
- s->ax25_dev = NULL;
spin_unlock_bh(&ax25_list_lock);
+ lock_sock(s->sk);
+ s->ax25_dev = NULL;
+ release_sock(s->sk);
ax25_disconnect(s, ENETUNREACH);
spin_lock_bh(&ax25_list_lock);