From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759587AbaDKQ5I (ORCPT ); Fri, 11 Apr 2014 12:57:08 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:56505 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1422749AbaDKQIy (ORCPT ); Fri, 11 Apr 2014 12:08:54 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Eric Dumazet , Rainer Weikusat , "David S. Miller" Subject: [PATCH 3.13 11/65] net: unix: non blocking recvmsg() should not return -EINTR Date: Fri, 11 Apr 2014 09:10:43 -0700 Message-Id: <20140411160959.280925799@linuxfoundation.org> X-Mailer: git-send-email 1.9.0 In-Reply-To: <20140411160957.714773410@linuxfoundation.org> References: <20140411160957.714773410@linuxfoundation.org> User-Agent: quilt/0.60-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.13-stable review patch. If anyone has any objections, please let me know. ------------------ From: Eric Dumazet [ Upstream commit de1443916791d75fdd26becb116898277bb0273f ] Some applications didn't expect recvmsg() on a non blocking socket could return -EINTR. This possibility was added as a side effect of commit b3ca9b02b00704 ("net: fix multithreaded signal handling in unix recv routines"). To hit this bug, you need to be a bit unlucky, as the u->readlock mutex is usually held for very small periods. Fixes: b3ca9b02b00704 ("net: fix multithreaded signal handling in unix recv routines") Signed-off-by: Eric Dumazet Cc: Rainer Weikusat Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- net/unix/af_unix.c | 17 ++++++++++++----- 1 file changed, 12 insertions(+), 5 deletions(-) --- a/net/unix/af_unix.c +++ b/net/unix/af_unix.c @@ -1785,8 +1785,11 @@ static int unix_dgram_recvmsg(struct kio goto out; err = mutex_lock_interruptible(&u->readlock); - if (err) { - err = sock_intr_errno(sock_rcvtimeo(sk, noblock)); + if (unlikely(err)) { + /* recvmsg() in non blocking mode is supposed to return -EAGAIN + * sk_rcvtimeo is not honored by mutex_lock_interruptible() + */ + err = noblock ? -EAGAIN : -ERESTARTSYS; goto out; } @@ -1911,6 +1914,7 @@ static int unix_stream_recvmsg(struct ki struct unix_sock *u = unix_sk(sk); struct sockaddr_un *sunaddr = msg->msg_name; int copied = 0; + int noblock = flags & MSG_DONTWAIT; int check_creds = 0; int target; int err = 0; @@ -1926,7 +1930,7 @@ static int unix_stream_recvmsg(struct ki goto out; target = sock_rcvlowat(sk, flags&MSG_WAITALL, size); - timeo = sock_rcvtimeo(sk, flags&MSG_DONTWAIT); + timeo = sock_rcvtimeo(sk, noblock); /* Lock the socket to prevent queue disordering * while sleeps in memcpy_tomsg @@ -1938,8 +1942,11 @@ static int unix_stream_recvmsg(struct ki } err = mutex_lock_interruptible(&u->readlock); - if (err) { - err = sock_intr_errno(timeo); + if (unlikely(err)) { + /* recvmsg() in non blocking mode is supposed to return -EAGAIN + * sk_rcvtimeo is not honored by mutex_lock_interruptible() + */ + err = noblock ? -EAGAIN : -ERESTARTSYS; goto out; }