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Date: Sun, 29 Sep 2024 19:09:41 -0700
From: Namhyung Kim <namhyung@kernel.org>
To: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Cc: Alexei Starovoitov <ast@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Andrii Nakryiko <andrii@kernel.org>,
	Martin KaFai Lau <martin.lau@linux.dev>,
	Eduard Zingerman <eddyz87@gmail.com>, Song Liu <song@kernel.org>,
	Yonghong Song <yonghong.song@linux.dev>,
	John Fastabend <john.fastabend@gmail.com>,
	KP Singh <kpsingh@kernel.org>, Stanislav Fomichev <sdf@fomichev.me>,
	Hao Luo <haoluo@google.com>, Jiri Olsa <jolsa@kernel.org>,
	LKML <linux-kernel@vger.kernel.org>, bpf <bpf@vger.kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Christoph Lameter <cl@linux.com>, Pekka Enberg <penberg@kernel.org>,
	David Rientjes <rientjes@google.com>,
	Joonsoo Kim <iamjoonsoo.kim@lge.com>,
	Vlastimil Babka <vbabka@suse.cz>,
	Roman Gushchin <roman.gushchin@linux.dev>,
	Hyeonggon Yoo <42.hyeyoo@gmail.com>, linux-mm <linux-mm@kvack.org>,
	Arnaldo Carvalho de Melo <acme@kernel.org>
Subject: Re: [RFC/PATCH bpf-next 2/3] mm/bpf: Add bpf_get_kmem_cache() kfunc
Message-ID: <ZvoIZYyyl73A-D51@google.com>
References: <20240927184133.968283-1-namhyung@kernel.org>
 <20240927184133.968283-3-namhyung@kernel.org>
 <CAADnVQKuR2-My5jYevwQS4K6QmOQVyfK3MYFngWMrc62ZET4ZA@mail.gmail.com>
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In-Reply-To: <CAADnVQKuR2-My5jYevwQS4K6QmOQVyfK3MYFngWMrc62ZET4ZA@mail.gmail.com>

On Sun, Sep 29, 2024 at 10:05:42AM -0700, Alexei Starovoitov wrote:
> On Fri, Sep 27, 2024 at 11:41 AM Namhyung Kim <namhyung@kernel.org> wrote:
> >
> > +__bpf_kfunc struct kmem_cache *bpf_get_kmem_cache(u64 addr)
> > +{
> > +       struct slab *slab;
> > +
> > +       slab = virt_to_slab((void *)(long)addr);
> > +       return slab ? slab->slab_cache : NULL;
> > +}
> 
> I think this needs more safety guards on 'addr'.
> It needs to check the valid range of 'addr' before doing virt_to_slab.

Ok, I think we can use virt_addr_valid() for that.

Thanks,
Namhyung