linux-kernel - Re: [PATCH V5 1/8] mm/slab: use unsigned long for orig

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] [day] [month] [year] [list]

Message-ID: <CAG_fn=Wyw-fGGQ802A1cUpkHHTnZi5gN7wZzRaF1s31SPOpC9g@mail.gmail.com>
Date: Fri, 9 Jan 2026 10:30:47 +0100
From: Alexander Potapenko <glider@...gle.com>
To: Harry Yoo <harry.yoo@...cle.com>
Cc: akpm@...ux-foundation.org, vbabka@...e.cz, andreyknvl@...il.com, 
	cl@...two.org, dvyukov@...gle.com, hannes@...xchg.org, linux-mm@...ck.org, 
	mhocko@...nel.org, muchun.song@...ux.dev, rientjes@...gle.com, 
	roman.gushchin@...ux.dev, ryabinin.a.a@...il.com, shakeel.butt@...ux.dev, 
	surenb@...gle.com, vincenzo.frascino@....com, yeoreum.yun@....com, 
	tytso@....edu, adilger.kernel@...ger.ca, linux-ext4@...r.kernel.org, 
	linux-kernel@...r.kernel.org, cgroups@...r.kernel.org, hao.li@...ux.dev, 
	stable@...r.kernel.org
Subject: Re: [PATCH V5 1/8] mm/slab: use unsigned long for orig_size to ensure
 proper metadata align

> > Instead of calculating the offset of the original size in several
> > places, should we maybe introduce a function that returns a pointer to
> > it?
>
> Good point.
>
> The calculation of various metadata offset (including the original size)
> is repeated in several places, and perhaps it's worth cleaning up,
> something like this:
>
> enum {
>   FREE_POINTER_OFFSET,
>   ALLOC_TRACK_OFFSET,
>   FREE_TRACK_OFFSET,
>   ORIG_SIZE_OFFSET,
>   KASAN_ALLOC_META_OFFSET,
>   OBJ_EXT_OFFSET,
>   FINAL_ALIGNMENT_PADDING_OFFSET,
>   ...
> };
>
> orig_size = *(unsigned long *)get_metadata_ptr(p, ORIG_SIZE_OFFSET);

An alternative would be to declare a struct containing all the
metadata fields and use offsetof() (or simply do a cast and access the
fields via the struct pointer)