linux-kernel - Re: [PATCH] mm/slab_common.c: fix possible spectre-v1 in kmalloc

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Message-ID: <20190529162532.GG18589@dhcp22.suse.cz>
Date:   Wed, 29 May 2019 18:25:32 +0200
From:   Michal Hocko <mhocko@...nel.org>
To:     Dianzhang Chen <dianzhangchen0@...il.com>
Cc:     cl@...ux.com, penberg@...nel.org, rientjes@...gle.com,
        iamjoonsoo.kim@....com, akpm@...ux-foundation.org,
        linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] mm/slab_common.c: fix possible spectre-v1 in
 kmalloc_slab()

On Wed 29-05-19 20:37:28, Dianzhang Chen wrote:
[...]
> @@ -1056,6 +1057,7 @@ struct kmem_cache *kmalloc_slab(size_t size, gfp_t flags)
>  		if (!size)
>  			return ZERO_SIZE_PTR;
>  
> +		size = array_index_nospec(size, 193);
>  		index = size_index[size_index_elem(size)];

What is this 193 magic number?
-- 
Michal Hocko
SUSE Labs