Received-SPF: pass (google.com: domain of linux-kernel+bounces-7647-linux.lists.archive=gmail.com@vger.kernel.org designates 147.75.80.249 as permitted sender) client-ip=147.75.80.249;
Precedence: bulk
MIME-Version: 1.0
References: <20231204-slub-cleanup-hooks-v1-0-88b65f7cd9d5@suse.cz>
 <20231204-slub-cleanup-hooks-v1-4-88b65f7cd9d5@suse.cz> <44421a37-4343-46d0-9e5c-17c2cd038cf2@linux.dev>
 <79e29576-12a2-a423-92f3-d8a7bcd2f0ce@suse.cz> <fdd11528-b0f8-48af-8141-15c4b1b01c65@linux.dev>
 <CANpmjNO1_LxE9w4m_Wa5xxc1R87LhnJSZ3DV59ia3-SdQUmtpw@mail.gmail.com>
 <CA+fCnZfhqQ+n0SsZU0RKEov3CkwTNJXM7JTMxtkrODmbJPskDQ@mail.gmail.com> <fec2561d-42fb-dd47-6e8f-3b55aaf39d85@suse.cz>
In-Reply-To: <fec2561d-42fb-dd47-6e8f-3b55aaf39d85@suse.cz>
From: Andrey Konovalov <andreyknvl@gmail.com>
Date: Thu, 21 Dec 2023 00:44:39 +0100
Message-ID: <CA+fCnZecUGRdqwfebu9C+hBN3_mW_VNhjm4FUXOo9Xak58NKdQ@mail.gmail.com>
Subject: Re: [PATCH 4/4] mm/slub: free KFENCE objects in slab_free_hook()
To: Vlastimil Babka <vbabka@suse.cz>
Cc: Marco Elver <elver@google.com>, Chengming Zhou <chengming.zhou@linux.dev>, 
	Christoph Lameter <cl@linux.com>, Pekka Enberg <penberg@kernel.org>, David Rientjes <rientjes@google.com>, 
	Joonsoo Kim <iamjoonsoo.kim@lge.com>, Andrew Morton <akpm@linux-foundation.org>, 
	Roman Gushchin <roman.gushchin@linux.dev>, Hyeonggon Yoo <42.hyeyoo@gmail.com>, 
	Alexander Potapenko <glider@google.com>, Dmitry Vyukov <dvyukov@google.com>, linux-mm@kvack.org, 
	linux-kernel@vger.kernel.org, kasan-dev@googlegroups.com
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable

On Tue, Dec 12, 2023 at 12:42=E2=80=AFPM Vlastimil Babka <vbabka@suse.cz> w=
rote:
>
> On 12/11/23 23:11, Andrey Konovalov wrote:
> > On Wed, Dec 6, 2023 at 3:45=E2=80=AFPM Marco Elver <elver@google.com> w=
rote:
> >>
> >> The is_kfence_address() implementation tolerates tagged addresses,
> >> i.e. if it receives a tagged non-kfence address, it will never return
> >> true.
>
> So just to be sure, it can't happen that a genuine kfence address would t=
hen
> become KASAN tagged and handed out, and thus when tested by
> is_kfence_address() it would be a false negative?

No, this should not happen. KFENCE objects never get tags assigned to them.