From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753963Ab3FDW6l (ORCPT ); Tue, 4 Jun 2013 18:58:41 -0400 Received: from 1wt.eu ([62.212.114.60]:35723 "EHLO 1wt.eu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753756Ab3FDWnY (ORCPT ); Tue, 4 Jun 2013 18:43:24 -0400 Message-Id: <20130604172136.975797600@1wt.eu> User-Agent: quilt/0.48-1 Date: Tue, 04 Jun 2013 19:24:11 +0200 From: Willy Tarreau To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Paul Moore , "David S. Miller" , Greg Kroah-Hartman , Willy Tarreau Subject: [ 161/184] unix: fix a race condition in unix_release() In-Reply-To: <58df134a4b98edf5b0073e2e1e988fe6@local> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 2.6.32-longterm review patch. If anyone has any objections, please let me know. ------------------ From: Paul Moore [ Upstream commit ded34e0fe8fe8c2d595bfa30626654e4b87621e0 ] As reported by Jan, and others over the past few years, there is a race condition caused by unix_release setting the sock->sk pointer to NULL before properly marking the socket as dead/orphaned. This can cause a problem with the LSM hook security_unix_may_send() if there is another socket attempting to write to this partially released socket in between when sock->sk is set to NULL and it is marked as dead/orphaned. This patch fixes this by only setting sock->sk to NULL after the socket has been marked as dead; I also take the opportunity to make unix_release_sock() a void function as it only ever returned 0/success. Dave, I think this one should go on the -stable pile. Special thanks to Jan for coming up with a reproducer for this problem. Reported-by: Jan Stancek Signed-off-by: Paul Moore Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman Signed-off-by: Willy Tarreau --- net/unix/af_unix.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-) diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c index db8d51a..d146b76 100644 --- a/net/unix/af_unix.c +++ b/net/unix/af_unix.c @@ -370,7 +370,7 @@ static void unix_sock_destructor(struct sock *sk) #endif } -static int unix_release_sock(struct sock *sk, int embrion) +static void unix_release_sock(struct sock *sk, int embrion) { struct unix_sock *u = unix_sk(sk); struct dentry *dentry; @@ -445,8 +445,6 @@ static int unix_release_sock(struct sock *sk, int embrion) if (unix_tot_inflight) unix_gc(); /* Garbage collect fds */ - - return 0; } static int unix_listen(struct socket *sock, int backlog) @@ -660,9 +658,10 @@ static int unix_release(struct socket *sock) if (!sk) return 0; + unix_release_sock(sk, 0); sock->sk = NULL; - return unix_release_sock(sk, 0); + return 0; } static int unix_autobind(struct socket *sock) -- 1.7.12.2.21.g234cd45.dirty