linux-kernel - Re: [PATCH] mm: Remove usercopy

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Date:   Mon, 7 Feb 2022 20:25:19 +0800
From:   Miaohe Lin <linmiaohe@...wei.com>
To:     Christophe Leroy <christophe.leroy@...roup.eu>
CC:     <linux-kernel@...r.kernel.org>, <linux-mm@...ck.org>,
        Stephen Kitt <steve@....org>,
        Kees Cook <keescook@...omium.org>,
        Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH] mm: Remove usercopy_warn()

On 2022/2/7 19:05, Christophe Leroy wrote:
> Users of usercopy_warn() were removed by
> commit 53944f171a89 ("mm: remove HARDENED_USERCOPY_FALLBACK")
> 
> Remote it.

s/Remote/Remove/

Except the above nit, this patch looks good to me. Thanks.

Reviewed-by: Miaohe Lin <linmiaohe@...wei.com>

> 
> Cc: Stephen Kitt <steve@....org>
> Cc: Kees Cook <keescook@...omium.org>
> Signed-off-by: Christophe Leroy <christophe.leroy@...roup.eu>
> ---
>  include/linux/uaccess.h |  2 --
>  mm/usercopy.c           | 11 -----------
>  2 files changed, 13 deletions(-)
> 
> diff --git a/include/linux/uaccess.h b/include/linux/uaccess.h
> index ac0394087f7d..bca27b4e5eb2 100644
> --- a/include/linux/uaccess.h
> +++ b/include/linux/uaccess.h
> @@ -401,8 +401,6 @@ static inline void user_access_restore(unsigned long flags) { }
>  #endif
>  
>  #ifdef CONFIG_HARDENED_USERCOPY
> -void usercopy_warn(const char *name, const char *detail, bool to_user,
> -		   unsigned long offset, unsigned long len);
>  void __noreturn usercopy_abort(const char *name, const char *detail,
>  			       bool to_user, unsigned long offset,
>  			       unsigned long len);
> diff --git a/mm/usercopy.c b/mm/usercopy.c
> index d0d268135d96..e7b0cb49daa1 100644
> --- a/mm/usercopy.c
> +++ b/mm/usercopy.c
> @@ -70,17 +70,6 @@ static noinline int check_stack_object(const void *obj, unsigned long len)
>   * kmem_cache_create_usercopy() function to create the cache (and
>   * carefully audit the whitelist range).
>   */
> -void usercopy_warn(const char *name, const char *detail, bool to_user,
> -		   unsigned long offset, unsigned long len)
> -{
> -	WARN_ONCE(1, "Bad or missing usercopy whitelist? Kernel memory %s attempt detected %s %s%s%s%s (offset %lu, size %lu)!\n",
> -		 to_user ? "exposure" : "overwrite",
> -		 to_user ? "from" : "to",
> -		 name ? : "unknown?!",
> -		 detail ? " '" : "", detail ? : "", detail ? "'" : "",
> -		 offset, len);
> -}
> -
>  void __noreturn usercopy_abort(const char *name, const char *detail,
>  			       bool to_user, unsigned long offset,
>  			       unsigned long len)
>