linux-kernel - Re: [PATCH RFC v2 01/20] mm/slab: add rcu_barrier() to kvfree_rcu_barrier_on

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: <CAJuCfpHCgyKTiPOZ_p76hTLRrZfQrkNh7XHJkEM0omWWCK2WQA@mail.gmail.com>
Date: Thu, 15 Jan 2026 23:52:01 +0000
From: Suren Baghdasaryan <surenb@...gle.com>
To: Vlastimil Babka <vbabka@...e.cz>
Cc: Harry Yoo <harry.yoo@...cle.com>, Petr Tesarik <ptesarik@...e.com>, 
	Christoph Lameter <cl@...two.org>, David Rientjes <rientjes@...gle.com>, 
	Roman Gushchin <roman.gushchin@...ux.dev>, Hao Li <hao.li@...ux.dev>, 
	Andrew Morton <akpm@...ux-foundation.org>, Uladzislau Rezki <urezki@...il.com>, 
	"Liam R. Howlett" <Liam.Howlett@...cle.com>, Sebastian Andrzej Siewior <bigeasy@...utronix.de>, 
	Alexei Starovoitov <ast@...nel.org>, linux-mm@...ck.org, linux-kernel@...r.kernel.org, 
	linux-rt-devel@...ts.linux.dev, bpf@...r.kernel.org, 
	kasan-dev@...glegroups.com, kernel test robot <oliver.sang@...el.com>, stable@...r.kernel.org
Subject: Re: [PATCH RFC v2 01/20] mm/slab: add rcu_barrier() to kvfree_rcu_barrier_on_cache()

On Wed, Jan 14, 2026 at 1:02 PM Vlastimil Babka <vbabka@...e.cz> wrote:
>
> On 1/14/26 12:14, Harry Yoo wrote:
> > For the record, an accurate analysis of the problem (as discussed
> > off-list):
> >
> > It turns out the object freed by sheaf_flush_unused() was in KASAN
> > percpu quarantine list (confirmed by dumping the list) by the time
> > __kmem_cache_shutdown() returns an error.
> >
> > Quarantined objects are supposed to be flushed by kasan_cache_shutdown(),
> > but things go wrong if the rcu callback (rcu_free_sheaf_nobarn()) is
> > processed after kasan_cache_shutdown() finishes.
> >
> > That's why rcu_barrier() in __kmem_cache_shutdown() didn't help,
> > because it's called after kasan_cache_shutdown().
> >
> > Calling rcu_barrier() in kvfree_rcu_barrier_on_cache() guarantees
> > that it'll be added to the quarantine list before kasan_cache_shutdown()
> > is called. So it's a valid fix!
>
> Thanks a lot! Will incorporate to commit log.
> This being KASAN-only means further reducing the urgency.

Thanks for the detailed explanation!

Reviewed-by: Suren Baghdasaryan <surenb@...gle.com>