linux-kernel - Re: [PATCH] mm/mremap: fix uninitialized return code

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Message-ID: <Z8ib8K9bPTbes0vn@google.com>
Date: Wed, 5 Mar 2025 18:46:08 +0000
From: Yosry Ahmed <yosry.ahmed@...ux.dev>
To: Arnd Bergmann <arnd@...nel.org>
Cc: Andrew Morton <akpm@...ux-foundation.org>,
	"Liam R. Howlett" <Liam.Howlett@...cle.com>,
	Lorenzo Stoakes <lorenzo.stoakes@...cle.com>,
	Arnd Bergmann <arnd@...db.de>, Vlastimil Babka <vbabka@...e.cz>,
	Jann Horn <jannh@...gle.com>,
	Pedro Falcato <pedro.falcato@...il.com>,
	David Hildenbrand <david@...hat.com>,
	Kefeng Wang <wangkefeng.wang@...wei.com>,
	Jeff Xu <jeffxu@...omium.org>, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] mm/mremap: fix uninitialized return code

On Wed, Mar 05, 2025 at 06:27:56PM +0100, Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@...db.de>
> 
> The 'err' variable is set in a conditinal branch and is not
> set otherwise:
> 
> mm/mremap.c:1017:7: error: variable 'err' is used uninitialized whenever 'if' condition is false [-Werror,-Wsometimes-uninitialized]
>  1017 |                 if (vma->vm_start != old_addr)
> 
> Set it to zero before the initial value is set.
> 
> Fixes: 3129f7896afb ("mm/mremap: initial refactor of move_vma()")

I think Andrew already fixed this:
https://lore.kernel.org/lkml/20250304151556.635d9041a7ca36f1960fe664@linux-foundation.org/

> Signed-off-by: Arnd Bergmann <arnd@...db.de>
> ---
>  mm/mremap.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/mm/mremap.c b/mm/mremap.c
> index 456849b9e7bd..9c51a2360d84 100644
> --- a/mm/mremap.c
> +++ b/mm/mremap.c
> @@ -1014,6 +1014,7 @@ static unsigned long prep_move_vma(struct vma_remap_struct *vrm)
>  		return -ENOMEM;
>  
>  	if (vma->vm_ops && vma->vm_ops->may_split) {
> +		err = 0;
>  		if (vma->vm_start != old_addr)
>  			err = vma->vm_ops->may_split(vma, old_addr);
>  		if (!err && vma->vm_end != old_addr + old_len)
> -- 
> 2.39.5
> 
>