linux-kernel - Re: [Xen-devel] [PATCH] xen/x86: Update topology map for PV VCPUs

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <57F65C2C02000078001155BB@prv-mh.provo.novell.com>
Date:   Thu, 06 Oct 2016 06:14:04 -0600
From:   "Jan Beulich" <JBeulich@...e.com>
To:     "Boris Ostrovsky" <boris.ostrovsky@...cle.com>
Cc:     <andrew.cooper3@...rix.com>, <david.vrabel@...rix.com>,
        <xen-devel@...ts.xenproject.org>,
        "Juergen Gross" <JGross@...e.com>, <linux-kernel@...r.kernel.org>,
        <stable@...r.kernel.org>
Subject: Re: [Xen-devel] [PATCH] xen/x86: Update topology map for PV
 VCPUs

>>> On 05.10.16 at 19:09, <boris.ostrovsky@...cle.com> wrote:
> Early during boot topology_update_package_map() computes
> logical_pkg_ids for all present processors.
> 
> Later, when processors are brought up, identify_cpu() updates
> these values based on phys_pkg_id which is a function of
> initial_apicid. On PV guests the latter may point to a
> non-existing node, causing logical_pkg_ids to be set to -1.
> 
> Intel's RAPL uses logical_pkg_id (as topology_logical_package_id())
> to index its arrays and therefore in this case will point to index
> 65535 (since logical_pkg_id is a u16). This could lead to either a
> crash or may actually access random memory location.

Another clear indication that such fields should never be touched
(and hence consumers either be fixed or disabled) when running as
PV guest under Xen.

Jan