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

Shachar Raindel
2015-04-02T10:52:52Z

Hi,

> -----Original Message-----
> From: Yann Droneaud [mailto:ydroneaud@opteya.com]
> Sent: Thursday, April 02, 2015 1:05 PM
> To: Shachar Raindel
> Cc: oss-security@lists.openwall.com; <linux-rdma@vger.kernel.org>
> (linux-rdma@vger.kernel.org); linux-kernel@vger.kernel.org;
> stable@vger.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