linux-kernel - Re: [PATCH 7/9] mm: kmemleak: erase page->s_mem in slab

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]

Message-ID: <73309bf-ca5b-b0ba-8ac-4be7dcc278b7@gentwo.de>
Date:   Thu, 26 Jan 2023 12:28:49 +0100 (CET)
From:   Christoph Lameter <cl@...two.de>
To:     George Prekas <george@...abrica.net>
cc:     linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        Catalin Marinas <catalin.marinas@....com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Pekka Enberg <penberg@...nel.org>,
        David Rientjes <rientjes@...gle.com>,
        Joonsoo Kim <iamjoonsoo.kim@....com>,
        Vlastimil Babka <vbabka@...e.cz>,
        Roman Gushchin <roman.gushchin@...ux.dev>,
        Hyeonggon Yoo <42.hyeyoo@...il.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        "Eric W. Biederman" <ebiederm@...ssion.com>,
        Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
        Andy Lutomirski <luto@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        "Liam R. Howlett" <Liam.Howlett@...cle.com>,
        Fenghua Yu <fenghua.yu@...el.com>,
        Andrei Vagin <avagin@...il.com>
Subject: Re: [PATCH 7/9] mm: kmemleak: erase page->s_mem in slab_destroy

On Mon, 23 Jan 2023, George Prekas wrote:

> The field s_mem of struct page is initialized with the virtual address
> of the page in function alloc_slabmgmt. If kmalloc allocates an object
> that starts on this page, then kmemleak knows that this object has 2
> references. On slab_destroy, s_mem should not continue referring to any
> allocated object in the future.

Nope.

s_mem is a pointer to an array of objects. It is not a pointer to a page.

If a slab-caches is used for slabmanagement then these objects
contain slab metadata which may be a bit confusing.