llc: fix netdevice reference leaks in llc_ui_bind()

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>

diff --git a/net/llc/af_llc.c b/net/llc/af_llc.c
index 26c00eb..c862560 100644 (file)
--- a/net/llc/af_llc.c
+++ b/net/llc/af_llc.c
@@ -311,6 +311,10 @@ static int llc_ui_autobind(struct socket *sock, struct sockaddr_llc *addr)
        sock_reset_flag(sk, SOCK_ZAPPED);
        rc = 0;
 out:
+       if (rc) {
+               dev_put_track(llc->dev, &llc->dev_tracker);
+               llc->dev = NULL;
+       }
        return rc;
 }
 
@@ -408,6 +412,10 @@ static int llc_ui_bind(struct socket *sock, struct sockaddr *uaddr, int addrlen)
 out_put:
        llc_sap_put(sap);
 out:
+       if (rc) {
+               dev_put_track(llc->dev, &llc->dev_tracker);
+               llc->dev = NULL;
+       }
        release_sock(sk);
        return rc;
 }