From: Eric Dumazet <edumazet@google.com>
Date: Tue, 22 Mar 2022 17:41:47 -0700
Subject: llc: fix netdevice reference leaks in llc_ui_bind()
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
Patch-mainline: v5.18-rc1
Git-commit: 764f4eb6846f5475f1244767d24d25dd86528a4a
References: CVE-2022-28356 bsc#1197391

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>
Acked-by: Michal Kubecek <mkubecek@suse.cz>

SLE/openSUSE: use dev_put() rather than dev_put_track() which was only
introduced in mainline 5.17-rc1.

---
 net/llc/af_llc.c | 8 ++++++++
 1 file changed, 8 insertions(+)

--- a/net/llc/af_llc.c
+++ b/net/llc/af_llc.c
@@ -303,6 +303,10 @@ 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;
 }
 
@@ -401,6 +405,10 @@ 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;
 }