From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <stable-owner@vger.kernel.org>
Received: from wtarreau.pck.nerim.net ([62.212.114.60]:54789 "EHLO 1wt.eu"
        rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP
        id S1752458AbcHULtz (ORCPT <rfc822;stable@vger.kernel.org>);
        Sun, 21 Aug 2016 07:49:55 -0400
Date: Sun, 21 Aug 2016 13:49:46 +0200
From: Willy Tarreau <w@1wt.eu>
To: Fabian Frederick <fabf@skynet.be>,
        Davidlohr Bueso <dbueso@suse.de>,
        Manfred Spraul <manfred@colorfullife.com>
Cc: linux-kernel@vger.kernel.org, stable@vger.kernel.org
Subject: Re: [PATCH 3.14 17/29] sysv, ipc: fix security-layer leaking
Message-ID: <20160821114946.GA30629@1wt.eu>
References: <20160814200731.375346059@linuxfoundation.org>
 <20160814200732.279601435@linuxfoundation.org>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20160814200732.279601435@linuxfoundation.org>
Sender: stable-owner@vger.kernel.org
List-ID: <stable.vger.kernel.org>

Hi guys,

On Sun, Aug 14, 2016 at 10:07:45PM +0200, Greg Kroah-Hartman wrote:
> 3.14-stable review patch.  If anyone has any objections, please let me know.
> 
> ------------------
> 
> From: Fabian Frederick <fabf@skynet.be>
> 
> commit 9b24fef9f0410fb5364245d6cc2bd044cc064007 upstream.
> 
> Commit 53dad6d3a8e5 ("ipc: fix race with LSMs") updated ipc_rcu_putref()
> to receive rcu freeing function but used generic ipc_rcu_free() instead
> of msg_rcu_free() which does security cleaning.
> 
> Running LTP msgsnd06 with kmemleak gives the following:
> 
>   cat /sys/kernel/debug/kmemleak
> 
>   unreferenced object 0xffff88003c0a11f8 (size 8):
>     comm "msgsnd06", pid 1645, jiffies 4294672526 (age 6.549s)
>     hex dump (first 8 bytes):
>       1b 00 00 00 01 00 00 00                          ........
>     backtrace:
>       kmemleak_alloc+0x23/0x40
>       kmem_cache_alloc_trace+0xe1/0x180
>       selinux_msg_queue_alloc_security+0x3f/0xd0
>       security_msg_queue_alloc+0x2e/0x40
>       newque+0x4e/0x150
>       ipcget+0x159/0x1b0
>       SyS_msgget+0x39/0x40
>       entry_SYSCALL_64_fastpath+0x13/0x8f
> 
> Manfred Spraul suggested to fix sem.c as well and Davidlohr Bueso to
> only use ipc_rcu_free in case of security allocation failure in newary()
> 
> Fixes: 53dad6d3a8e ("ipc: fix race with LSMs")
> Link: http://lkml.kernel.org/r/1470083552-22966-1-git-send-email-fabf@skynet.be
> Signed-off-by: Fabian Frederick <fabf@skynet.be>
> Cc: Davidlohr Bueso <dbueso@suse.de>
> Cc: Manfred Spraul <manfred@colorfullife.com>
> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

The patch above was tagged for stable v3.12+, however it references a fix
that was backported in 3.10.16 as commit e84ca333, so I'm unsure whether
3.10 is affected or not. It *seems* to me that I should replace remaining
instances of ipc_rcu_free with sem_rcu_free in sem.c, and with msg_rcu_free
in msg.c, but I'd prefer a confirmation. For now I'm postponing this fix,
any hint would be much appreciated.

Thanks,
Willy