[SRU][Impish][PATCH 1/1] llc: fix netdevice reference leaks in llc_ui_bind()

[Cengiz Can]

From: Eric Dumazet <edumazet at 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 at google.com>
Reported-by: 赵子轩 <beraphin at gmail.com>
Reported-by: Stoyan Manolov <smanolov at suse.de>
Link: https://lore.kernel.org/r/20220323004147.1990845-1-eric.dumazet@gmail.com
Signed-off-by: Jakub Kicinski <kuba at kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
CVE-2022-28356
(cherry picked from 571df3393f523b59cba87e2f3e80a3a624030f9c linux-5.10.y)
Signed-off-by: Cengiz Can <cengiz.can at canonical.com>
---
 net/llc/af_llc.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/net/llc/af_llc.c b/net/llc/af_llc.c
index ac5cadd02cfa..2fdb72a26fa8 100644
--- 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(llc->dev);
+		llc->dev = NULL;
+	}
 	return rc;
 }
 
@@ -409,6 +413,10 @@ 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;
 }
-- 
2.34.1