From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:37030 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728020AbeJNXZH (ORCPT ); Sun, 14 Oct 2018 19:25:07 -0400 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "Cong Wang" , "kernel test robot" , "David S. Miller" Date: Sun, 14 Oct 2018 16:25:41 +0100 Message-ID: Subject: [PATCH 3.16 190/366] llc: fix NULL pointer deref for SOCK_ZAPPED In-Reply-To: Sender: stable-owner@vger.kernel.org List-ID: 3.16.60-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Cong Wang commit 3a04ce7130a7e5dad4e78d45d50313747f8c830f upstream. 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 Signed-off-by: Cong Wang Signed-off-by: David S. Miller Signed-off-by: Ben Hutchings --- 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);