linux-kernel - Re: [RFC/PATCH bpf-next 2/3] mm/bpf: Add bpf_get_kmem

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Message-ID: <CAADnVQKuR2-My5jYevwQS4K6QmOQVyfK3MYFngWMrc62ZET4ZA@mail.gmail.com>
Date: Sun, 29 Sep 2024 10:05:42 -0700
From: Alexei Starovoitov <alexei.starovoitov@...il.com>
To: Namhyung Kim <namhyung@...nel.org>
Cc: Alexei Starovoitov <ast@...nel.org>, Daniel Borkmann <daniel@...earbox.net>, 
	Andrii Nakryiko <andrii@...nel.org>, Martin KaFai Lau <martin.lau@...ux.dev>, 
	Eduard Zingerman <eddyz87@...il.com>, Song Liu <song@...nel.org>, 
	Yonghong Song <yonghong.song@...ux.dev>, John Fastabend <john.fastabend@...il.com>, 
	KP Singh <kpsingh@...nel.org>, Stanislav Fomichev <sdf@...ichev.me>, Hao Luo <haoluo@...gle.com>, 
	Jiri Olsa <jolsa@...nel.org>, LKML <linux-kernel@...r.kernel.org>, 
	bpf <bpf@...r.kernel.org>, Andrew Morton <akpm@...ux-foundation.org>, 
	Christoph Lameter <cl@...ux.com>, 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>, 
	linux-mm <linux-mm@...ck.org>, Arnaldo Carvalho de Melo <acme@...nel.org>
Subject: Re: [RFC/PATCH bpf-next 2/3] mm/bpf: Add bpf_get_kmem_cache() kfunc

On Fri, Sep 27, 2024 at 11:41 AM Namhyung Kim <namhyung@...nel.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.