Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759495AbcCVLOA (ORCPT ); Tue, 22 Mar 2016 07:14:00 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:56597 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758740AbcCVKmM (ORCPT ); Tue, 22 Mar 2016 06:42:12 -0400 From: Luis Henriques To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: Rainer Weikusat , "David S. Miller" , Luis Henriques Subject: [PATCH 3.16.y-ckt 052/142] af_unix: Guard against other == sk in unix_dgram_sendmsg Date: Tue, 22 Mar 2016 10:39:41 +0000 Message-Id: <1458643271-4227-53-git-send-email-luis.henriques@canonical.com> In-Reply-To: <1458643271-4227-1-git-send-email-luis.henriques@canonical.com> References: <1458643271-4227-1-git-send-email-luis.henriques@canonical.com> X-Extended-Stable: 3.16 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2090 Lines: 51 3.16.7-ckt26 -stable review patch. If anyone has any objections, please let me know. ---8<------------------------------------------------------------ From: Rainer Weikusat commit a5527dda344fff0514b7989ef7a755729769daa1 upstream. 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: Luis Henriques --- 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 5a5721a7f9e0..3e6f0eba8216 100644 --- a/net/unix/af_unix.c +++ b/net/unix/af_unix.c @@ -1722,7 +1722,12 @@ 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);