linux-kernel - RE: CVE-2014-8159 kernel: infiniband: uverbs: unprotected physical memory access

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Date:	Thu, 2 Apr 2015 10:52:52 +0000
From:	Shachar Raindel <raindel@...lanox.com>
To:	Yann Droneaud <ydroneaud@...eya.com>
CC:	"oss-security@...ts.openwall.com" <oss-security@...ts.openwall.com>,
	"<linux-rdma@...r.kernel.org> (linux-rdma@...r.kernel.org)" 
	<linux-rdma@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"stable@...r.kernel.org" <stable@...r.kernel.org>
Subject: RE: CVE-2014-8159 kernel: infiniband: uverbs: unprotected physical
 memory access

Hi,

> -----Original Message-----
> From: Yann Droneaud [mailto:ydroneaud@...eya.com]
> Sent: Thursday, April 02, 2015 1:05 PM
> To: Shachar Raindel
> Cc: oss-security@...ts.openwall.com; <linux-rdma@...r.kernel.org>
> (linux-rdma@...r.kernel.org); linux-kernel@...r.kernel.org;
> stable@...r.kernel.org
> Subject: Re: CVE-2014-8159 kernel: infiniband: uverbs: unprotected
> physical memory access
> 
> Hi,
> 
> Le mercredi 18 mars 2015 à 17:39 +0000, Shachar Raindel a écrit :
> > Hi,
> >

<snipped long e-mail>
 
> > +	/*
> > +	 * If the combination of the addr and size requested for this
> memory
> > +	 * region causes an integer overflow, return error.
> > +	 */
> > +	if ((PAGE_ALIGN(addr + size) <= size) ||
> > +	    (PAGE_ALIGN(addr + size) <= addr))
> > +		return ERR_PTR(-EINVAL);
> > +
> 
> Can access_ok() be used here ?
> 
>          if (!access_ok(writable ? VERIFY_WRITE : VERIFY_READ,
>                         addr, size))
>                   return ERR_PTR(-EINVAL);
> 

No, this will break the current ODP semantics.

ODP allows the user to register memory that is not accessible yet.
This is a critical design feature, as it allows avoiding holding
a registration cache. Adding this check will break the behavior,
forcing memory to be all accessible when registering an ODP MR.

Thanks,
--Shachar