llc: fix netdevice reference leaks in llc_ui_bind()

BugLink: https://bugs.launchpad.net/bugs/1969106
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>
(cherry picked from commit e9072996108387ab19b497f5b557c93f98d96b0b)
Signed-off-by: Paolo Pisati <paolo.pisati@canonical.com>

diff --git a/net/llc/af_llc.c b/net/llc/af_llc.c
index 3086f4a6ae683f1119d4813648bf9fd9ba215436..fb88971a40aedcefa135af8b1be4c569fa637d2f 100644 (file)
--- a/net/llc/af_llc.c
+++ b/net/llc/af_llc.c
@@ -310,6 +310,10 @@ 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(llc->dev);
+               llc->dev = NULL;
+       }
        return rc;
 }
 
@@ -407,6 +411,10 @@ static int llc_ui_bind(struct socket *sock, struct sockaddr *uaddr, int addrlen)
 out_put:
        llc_sap_put(sap);
 out:
+       if (rc) {
+               dev_put(llc->dev);
+               llc->dev = NULL;
+       }
        release_sock(sk);
        return rc;
 }