Re: [RFC PATCH -next V3 2/6] arm64: fix types in copy_highpage()

[Kefeng Wang]

On 2022/4/12 15:25, Tong Tiangen wrote:
> In copy_highpage() the `kto` and `kfrom` local variables are pointers to
> struct page, but these are used to hold arbitrary pointers to kernel memory
> . Each call to page_address() returns a void pointer to memory associated
> with the relevant page, and copy_page() expects void pointers to this
> memory.
>
> This inconsistency was introduced in commit 2563776b41c3 ("arm64: mte:
> Tags-aware copy_{user_,}highpage() implementations") and while this
> doesn't appear to be harmful in practice it is clearly wrong.
>
> Correct this by making `kto` and `kfrom` void pointers.
Reviewed-by: Kefeng Wang <wangkefeng.wang@xxxxxxxxxx>

> Fixes: 2563776b41c3 ("arm64: mte: Tags-aware copy_{user_,}highpage() implementations")
> Signed-off-by: Tong Tiangen <tongtiangen@xxxxxxxxxx>
> Acked-by: Mark Rutland <mark.rutland@xxxxxxx>
> ---
>   arch/arm64/mm/copypage.c | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/arch/arm64/mm/copypage.c b/arch/arm64/mm/copypage.c
> index b5447e53cd73..0dea80bf6de4 100644
> --- a/arch/arm64/mm/copypage.c
> +++ b/arch/arm64/mm/copypage.c
> @@ -16,8 +16,8 @@
>   
>   void copy_highpage(struct page *to, struct page *from)
>   {
> -	struct page *kto = page_address(to);
> -	struct page *kfrom = page_address(from);
> +	void *kto = page_address(to);
> +	void *kfrom = page_address(from);
>   
>   	copy_page(kto, kfrom);
>