linux-kernel - Re: [PATCH 7/9] Pmalloc Rare Write: modify selected pools

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: Windows password security audit tool. GUI, reports in PDF.

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

Date:   Tue, 24 Apr 2018 14:32:36 +0200
From:   lazytyped <lazytyped@...il.com>
To:     Matthew Wilcox <willy@...radead.org>,
        Igor Stoppa <igor.stoppa@...il.com>
Cc:     keescook@...omium.org, paul@...l-moore.com, sds@...ho.nsa.gov,
        mhocko@...nel.org, corbet@....net, labbott@...hat.com,
        linux-cc=david@...morbit.com, --cc=rppt@...ux.vnet.ibm.com,
        --security-module@...r.kernel.org, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org, kernel-hardening@...ts.openwall.com,
        Igor Stoppa <igor.stoppa@...wei.com>,
        Carlos Chinea Perez <carlos.chinea.perez@...wei.com>,
        Remi Denis Courmont <remi.denis.courmont@...wei.com>
Subject: Re: [PATCH 7/9] Pmalloc Rare Write: modify selected pools



On 4/24/18 1:50 PM, Matthew Wilcox wrote:
> struct modifiable_data {
> 	struct immutable_data *d;
> 	...
> };
>
> Then allocate a new pool, change d and destroy the old pool.

With the above, you have just shifted the target of the arbitrary write
from the immutable data itself to the pointer to the immutable data, so
got no security benefit.

The goal of the patch is to reduce the window when stuff is writeable,
so that an arbitrary write is likely to hit the time when data is read-only.


       -  Enrico