linux-kernel - Re: [PATCH 3.14 11/23] pipe: Fix buffer offset after partially failed read

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Message-ID: <094a36ed-163a-8ced-afd2-85bb74d21f4f@suse.cz>
Date:	Tue, 7 Jun 2016 15:50:18 +0200
From:	Jiri Slaby <jslaby@...e.cz>
To:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	linux-kernel@...r.kernel.org
Cc:	stable@...r.kernel.org, Ben Hutchings <ben@...adent.org.uk>,
	Willy Tarreau <w@....eu>
Subject: Re: [PATCH 3.14 11/23] pipe: Fix buffer offset after partially failed
 read

On 06/05/2016, 11:40 PM, Greg Kroah-Hartman wrote:
> 3.14-stable review patch.  If anyone has any objections, please let me know.
> 
> ------------------
> 
> From: Ben Hutchings <ben@...adent.org.uk>
> 
> commit feae3ca2e5e1a8f44aa6290255d3d9709985d0b2 upstream.

This is not a SHA of an upstream commit ;).

> Quoting the RHEL advisory:
> 
>> It was found that the fix for CVE-2015-1805 incorrectly kept buffer
>> offset and buffer length in sync on a failed atomic read, potentially
>> resulting in a pipe buffer state corruption. A local, unprivileged user
>> could use this flaw to crash the system or leak kernel memory to user
>> space. (CVE-2016-0774, Moderate)
> 
> The same flawed fix was applied to stable branches from 2.6.32.y to
> 3.14.y inclusive, and I was able to reproduce the issue on 3.2.y.
> We need to give pipe_iov_copy_to_user() a separate offset variable
> and only update the buffer offset if it succeeds.
> 
> References: https://rhn.redhat.com/errata/RHSA-2016-0103.html
> Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
> Cc: Willy Tarreau <w@....eu>
> Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

thanks,
-- 
js
suse labs