Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934304AbcCPIQ3 (ORCPT ); Wed, 16 Mar 2016 04:16:29 -0400 Received: from mail.kernel.org ([198.145.29.136]:60792 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S966048AbcCPINL (ORCPT ); Wed, 16 Mar 2016 04:13:11 -0400 From: lizf@kernel.org To: stable@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Rainer Weikusat , "David S. Miller" , Zefan Li Subject: [PATCH 3.4 100/107] af_unix: Guard against other == sk in unix_dgram_sendmsg Date: Wed, 16 Mar 2016 16:06:34 +0800 Message-Id: <1458115601-5762-100-git-send-email-lizf@kernel.org> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1458115541-5712-1-git-send-email-lizf@kernel.org> References: <1458115541-5712-1-git-send-email-lizf@kernel.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2019 Lines: 54 From: Rainer Weikusat 3.4.111-rc1 review patch. If anyone has any objections, please let me know. ------------------ 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: Zefan Li --- 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 9e120d7..de07f94 100644 --- a/net/unix/af_unix.c +++ b/net/unix/af_unix.c @@ -1693,7 +1693,12 @@ 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); -- 1.9.1