linux-kernel - Re: [RFC] mm/memblock.c: using uninitialized value idx in memblock_add

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Message-ID: <20170912150737.envdkppnpx5xskfy@dhcp22.suse.cz>
Date:   Tue, 12 Sep 2017 17:07:37 +0200
From:   Michal Hocko <mhocko@...nel.org>
To:     gurugio@...il.com
Cc:     linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        Gioh Kim <gurugio@...mail.net>,
        Gioh Kim <gi-oh.kim@...fitbricks.com>
Subject: Re: [RFC] mm/memblock.c: using uninitialized value idx in
 memblock_add_range()

On Sat 09-09-17 00:15:33, gurugio@...il.com wrote:
> From: Gioh Kim <gurugio@...mail.net>
> 
> In memblock_add_range(), idx variable is a local value
> but I cannot find initialization of idx value.
> I checked idx value on my Qemu emulator. It was zero.
> Is there any hidden initialization code?

Yes for_each_memblock_type. Ugly as hell! Something to clean up I guess.
Just make the index explicit argument of the macro.

> 
> Signed-off-by: Gioh Kim <gi-oh.kim@...fitbricks.com>
> ---
>  mm/memblock.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/mm/memblock.c b/mm/memblock.c
> index 7b8a5db..23374bc 100644
> --- a/mm/memblock.c
> +++ b/mm/memblock.c
> @@ -515,7 +515,7 @@ int __init_memblock memblock_add_range(struct memblock_type *type,
>  	bool insert = false;
>  	phys_addr_t obase = base;
>  	phys_addr_t end = base + memblock_cap_size(base, &size);
> -	int idx, nr_new;
> +	int idx = 0, nr_new;
>  	struct memblock_region *rgn;
>  
>  	if (!size)
> -- 
> 2.7.4

-- 
Michal Hocko
SUSE Labs