linux-kernel - Re: CVE-2015-1805 and 3.14-longterm?

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Date:	Fri, 14 Aug 2015 21:17:49 +0200
From:	Sven Joachim <svenjoac@....de>
To:	Greg KH <greg@...ah.com>
Cc:	Dick Snippe <Dick.Snippe@....nl>, stable@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: CVE-2015-1805 and 3.14-longterm?

On 2015-08-14 18:55 +0200, Greg KH wrote:

> On Thu, Jul 02, 2015 at 10:19:34AM +0200, Dick Snippe wrote:
>> Hello,
>> 
>> I'm sorry to bother you with this, but lwn.net reported a rather serious
>> security issue a couple of weeks ago:
>> 
>> http://lwn.net/Articles/646590/
>> https://bugzilla.redhat.com/show_bug.cgi?id=1202855
>> CVE-2015-1805
>> "It was found that the Linux kernel's implementation of vectored pipe
>> read and write functionality did not take into account the I/O vectors
>> that were already processed when retrying after a failed atomic access
>> operation, potentially resulting in memory corruption due to an I/O
>> vector array overrun. A local, unprivileged user could use this flaw to
>> crash the system or, potentially, escalate their privileges on the
>> system."
>> 
>> It appears that these upstream fixes haven't made it to 3.14.4[456]:
>> 
>> http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=f0d1bec9d58d4c038d0ac958c9af82be6eb18045
>> http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=637b58c2887e5e57850865839cc75f59184b23d1
>> 
>> I'm just a (very happy!) user of the -longterm kernels, so I don't
>> know how this normally works. But it would appear that this bug still
>> exists in the -longterm kernels.
>
> I think, and I might be wrong here, but because
> 637b58c2887e5e57850865839cc75f59184b23d1 (switch pipe_read() to
> copy_page_to_iter()) is not in the 3.14-stable tree (it showed up in
> 3.15), that f0d1bec9d58d4c038d0ac958c9af82be6eb18045 (new helper:
> copy_page_from_iter()) isn't needed (it showed up in 3.16).
>
> So is this a problem in the 3.14-stable tree?

It seems to have been fixed by 6b17faf3d5fa6a727c40613bdf24d73b2a59df27
(pipe: iovec: Fix memory corruption when retrying atomic copy as
non-atomic) in 3.14.46.  That fix is also in 3.10.82.

Cheers,
       Sven
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