Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759898AbcCDJsj (ORCPT ); Fri, 4 Mar 2016 04:48:39 -0500 Received: from mx2.suse.de ([195.135.220.15]:59668 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758872AbcCDJCx (ORCPT ); Fri, 4 Mar 2016 04:02:53 -0500 X-Amavis-Alert: BAD HEADER SECTION, Duplicate header field: "References" From: Jiri Slaby To: stable@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Rainer Weikusat , "David S . Miller" , Jiri Slaby Subject: [PATCH 3.12 018/116] af_unix: Guard against other == sk in unix_dgram_sendmsg Date: Fri, 4 Mar 2016 10:01:03 +0100 Message-Id: <6126da76d00e981cca46080c464f9c309067b022.1457082108.git.jslaby@suse.cz> X-Mailer: git-send-email 2.7.2 In-Reply-To: References: In-Reply-To: References: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2026 Lines: 53 From: Rainer Weikusat 3.12-stable review patch. If anyone has any objections, please let me know. =============== [ Upstream commit a5527dda344fff0514b7989ef7a755729769daa1 ] The unix_dgram_sendmsg routine use the following test if (unlikely(unix_peer(other) != sk && unix_recvq_full(other))) { to determine if sk and other are in an n:1 association (either established via connect or by using sendto to send messages to an unrelated socket identified by address). This isn't correct as the specified address could have been bound to the sending socket itself or because this socket could have been connected to itself by the time of the unix_peer_get but disconnected before the unix_state_lock(other). In both cases, the if-block would be entered despite other == sk which might either block the sender unintentionally or lead to trying to unlock the same spin lock twice for a non-blocking send. Add a other != sk check to guard against this. Fixes: 7d267278a9ec ("unix: avoid use-after-free in ep_remove_wait_queue") Reported-By: Philipp Hahn Signed-off-by: Rainer Weikusat Tested-by: Philipp Hahn Signed-off-by: David S. Miller Signed-off-by: Jiri Slaby --- net/unix/af_unix.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c index 5fb2d2af3e52..c5536b7d8ce4 100644 --- a/net/unix/af_unix.c +++ b/net/unix/af_unix.c @@ -1700,7 +1700,12 @@ restart_locked: goto out_unlock; } - if (unlikely(unix_peer(other) != sk && unix_recvq_full(other))) { + /* other == sk && unix_peer(other) != sk if + * - unix_peer(sk) == NULL, destination address bound to sk + * - unix_peer(sk) == sk by time of get but disconnected before lock + */ + if (other != sk && + unlikely(unix_peer(other) != sk && unix_recvq_full(other))) { if (timeo) { timeo = unix_wait_for_peer(other, timeo); -- 2.7.2