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Message-Id: <20180427135658.104287309@linuxfoundation.org>
Date: Fri, 27 Apr 2018 15:58:43 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-kernel@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
stable@...r.kernel.org, kernel test robot <lkp@...el.com>,
Cong Wang <xiyou.wangcong@...il.com>,
"David S. Miller" <davem@...emloft.net>
Subject: [PATCH 4.4 41/50] llc: fix NULL pointer deref for SOCK_ZAPPED
4.4-stable review patch. If anyone has any objections, please let me know.
------------------
From: Cong Wang <xiyou.wangcong@...il.com>
[ Upstream commit 3a04ce7130a7e5dad4e78d45d50313747f8c830f ]
For SOCK_ZAPPED socket, we don't need to care about llc->sap,
so we should just skip these refcount functions in this case.
Fixes: f7e43672683b ("llc: hold llc_sap before release_sock()")
Reported-by: kernel test robot <lkp@...el.com>
Signed-off-by: Cong Wang <xiyou.wangcong@...il.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
net/llc/af_llc.c | 21 ++++++++++++---------
1 file changed, 12 insertions(+), 9 deletions(-)
--- a/net/llc/af_llc.c
+++ b/net/llc/af_llc.c
@@ -187,7 +187,6 @@ static int llc_ui_release(struct socket
{
struct sock *sk = sock->sk;
struct llc_sock *llc;
- struct llc_sap *sap;
if (unlikely(sk == NULL))
goto out;
@@ -198,15 +197,19 @@ static int llc_ui_release(struct socket
llc->laddr.lsap, llc->daddr.lsap);
if (!llc_send_disc(sk))
llc_ui_wait_for_disc(sk, sk->sk_rcvtimeo);
- sap = llc->sap;
- /* Hold this for release_sock(), so that llc_backlog_rcv() could still
- * use it.
- */
- llc_sap_hold(sap);
- if (!sock_flag(sk, SOCK_ZAPPED))
+ if (!sock_flag(sk, SOCK_ZAPPED)) {
+ struct llc_sap *sap = llc->sap;
+
+ /* Hold this for release_sock(), so that llc_backlog_rcv()
+ * could still use it.
+ */
+ llc_sap_hold(sap);
llc_sap_remove_socket(llc->sap, sk);
- release_sock(sk);
- llc_sap_put(sap);
+ release_sock(sk);
+ llc_sap_put(sap);
+ } else {
+ release_sock(sk);
+ }
if (llc->dev)
dev_put(llc->dev);
sock_put(sk);
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