[PATCH 4.14 06/17] llc: fix netdevice reference leaks in llc_ui_bind()

Greg Kroah-Hartman
2022-03-25T15:07:58Z

From: Eric Dumazet <edumazet@google.com>

commit 764f4eb6846f5475f1244767d24d25dd86528a4a upstream.

Whenever llc_ui_bind() and/or llc_ui_autobind()
took a reference on a netdevice but subsequently fail,
they must properly release their reference
or risk the infamous message from unregister_netdevice()
at device dismantle.

unregister_netdevice: waiting for eth0 to become free. Usage count = 3

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: 赵子轩 <beraphin@gmail.com>
Reported-by: Stoyan Manolov <smanolov@suse.de>
Link: https://lore.kernel.org/r/20220323004147.1990845-1-eric.dumazet@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
net/llc/af_llc.c | 8 ++++++++
1 file changed, 8 insertions(+)

--- a/net/llc/af_llc.c
+++ b/net/llc/af_llc.c
@@ -311,6 +311,10 @@ static int llc_ui_autobind(struct socket
sock_reset_flag(sk, SOCK_ZAPPED);
rc = 0;
out:
+ if (rc) {
+ dev_put(llc->dev);
+ llc->dev = NULL;
+ }
return rc;
}

@@ -410,6 +414,10 @@ static int llc_ui_bind(struct socket *so
out_put:
llc_sap_put(sap);
out:
+ if (rc) {
+ dev_put(llc->dev);
+ llc->dev = NULL;
+ }
release_sock(sk);
return rc;
}