linux-kernel - Re: [PATCH 13/16] mm/page_alloc: init local variable buddy

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Message-ID: <YyLXZDc2PrjITRe6@localhost.localdomain>
Date:   Thu, 15 Sep 2022 09:42:28 +0200
From:   Oscar Salvador <osalvador@...e.de>
To:     Miaohe Lin <linmiaohe@...wei.com>
Cc:     akpm@...ux-foundation.org, david@...hat.com, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 13/16] mm/page_alloc: init local variable buddy_pfn

On Fri, Sep 09, 2022 at 05:24:48PM +0800, Miaohe Lin wrote:
> The local variable buddy_pfn could be passed to buddy_merge_likely()
> without initialization if the passed in order is MAX_ORDER - 1. This
> looks buggy but buddy_pfn won't be used in this case as there's a
> order >= MAX_ORDER - 2 check. Init buddy_pfn to 0 anyway to avoid
> possible future misuse.
> 
> Signed-off-by: Miaohe Lin <linmiaohe@...wei.com>

Reviewed-by: Oscar Salvador <osalvador@...e.de>

> ---
>  mm/page_alloc.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index e1c7f98cff96..63ad25e86010 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -1113,7 +1113,7 @@ static inline void __free_one_page(struct page *page,
>  		int migratetype, fpi_t fpi_flags)
>  {
>  	struct capture_control *capc = task_capc(zone);
> -	unsigned long buddy_pfn;
> +	unsigned long buddy_pfn = 0;
>  	unsigned long combined_pfn;
>  	struct page *buddy;
>  	bool to_tail;
> -- 
> 2.23.0
> 

-- 
Oscar Salvador
SUSE Labs