From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932557AbcC2UJu (ORCPT ); Tue, 29 Mar 2016 16:09:50 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:45202 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758058AbcC2UE5 (ORCPT ); Tue, 29 Mar 2016 16:04:57 -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, "David S. Miller" , "Rainer Weikusat" , "Joseph Salisbury" Date: Tue, 29 Mar 2016 20:18:22 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.2 20/62] af_unix: Don't set err in unix_stream_read_generic unless there was an error In-Reply-To: X-SA-Exim-Connect-IP: 213.146.164.225 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.2.79-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Rainer Weikusat commit 1b92ee3d03af6643df395300ba7748f19ecdb0c5 upstream. The present unix_stream_read_generic contains various code sequences of the form err = -EDISASTER; if () goto out; This has the unfortunate side effect of possibly causing the error code to bleed through to the final out: return copied ? : err; and then to be wrongly returned if no data was copied because the caller didn't supply a data buffer, as demonstrated by the program available at http://pad.lv/1540731 Change it such that err is only set if an error condition was detected. Fixes: 3822b5c2fc62 ("af_unix: Revert 'lock_interruptible' in stream receive code") Reported-by: Joseph Salisbury Signed-off-by: Rainer Weikusat Signed-off-by: David S. Miller [bwh: Backported to 3.2: adjust context] Signed-off-by: Ben Hutchings --- net/unix/af_unix.c | 16 ++++++++++------ 1 file changed, 10 insertions(+), 6 deletions(-) --- a/net/unix/af_unix.c +++ b/net/unix/af_unix.c @@ -2059,13 +2059,15 @@ static int unix_stream_recvmsg(struct ki int err = 0; long timeo; - err = -EINVAL; - if (sk->sk_state != TCP_ESTABLISHED) + if (unlikely(sk->sk_state != TCP_ESTABLISHED)) { + err = -EINVAL; goto out; + } - err = -EOPNOTSUPP; - if (flags&MSG_OOB) + if (unlikely(flags & MSG_OOB)) { + err = -EOPNOTSUPP; goto out; + } target = sock_rcvlowat(sk, flags&MSG_WAITALL, size); timeo = sock_rcvtimeo(sk, noblock); @@ -2107,9 +2109,11 @@ static int unix_stream_recvmsg(struct ki goto unlock; unix_state_unlock(sk); - err = -EAGAIN; - if (!timeo) + if (!timeo) { + err = -EAGAIN; break; + } + mutex_unlock(&u->readlock); timeo = unix_stream_data_wait(sk, timeo);