linux-kernel - Re: [PATCH v3 4/4] mm: huge_memory: Use strscpy() instead of strcpy()

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Message-ID: <CAGsJ_4zMppHY29XXepOVTdEu2-1U6mGyZ8FqXZfP_in+2T3NAA@mail.gmail.com>
Date: Thu, 31 Oct 2024 12:07:44 +1300
From: Barry Song <baohua@...nel.org>
To: Maíra Canal <mcanal@...lia.com>
Cc: Jonathan Corbet <corbet@....net>, Andrew Morton <akpm@...ux-foundation.org>, 
	Hugh Dickins <hughd@...gle.com>, David Hildenbrand <david@...hat.com>, Ryan Roberts <ryan.roberts@....com>, 
	Baolin Wang <baolin.wang@...ux.alibaba.com>, Lance Yang <ioworker0@...il.com>, linux-mm@...ck.org, 
	linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org, 
	kernel-dev@...lia.com
Subject: Re: [PATCH v3 4/4] mm: huge_memory: Use strscpy() instead of strcpy()

On Thu, Oct 31, 2024 at 2:03 AM Maíra Canal <mcanal@...lia.com> wrote:
>
> Replace strcpy() with strscpy() in mm/huge_memory.c
>
> strcpy() has been deprecated because it is generally unsafe, so help to
> eliminate it from the kernel source.
>
> Link: https://github.com/KSPP/linux/issues/88
> Signed-off-by: Maíra Canal <mcanal@...lia.com>
> ---
>  mm/huge_memory.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/mm/huge_memory.c b/mm/huge_memory.c
> index f92068864469..8f41a694433c 100644
> --- a/mm/huge_memory.c
> +++ b/mm/huge_memory.c
> @@ -989,7 +989,7 @@ static int __init setup_thp_anon(char *str)
>
>         if (!str || strlen(str) + 1 > PAGE_SIZE)
>                 goto err;
> -       strcpy(str_dup, str);
> +       strscpy(str_dup, str);

What is the difference between strcpy and strscpy without a size parameter?

we have already a check and goto err. strcpy() is entirely safe.
         if (!str || strlen(str) + 1 > PAGE_SIZE)
                 goto err;

My understanding is that we don't need this patch.

>
>         always = huge_anon_orders_always;
>         madvise = huge_anon_orders_madvise;
> @@ -4175,7 +4175,7 @@ static ssize_t split_huge_pages_write(struct file *file, const char __user *buf,
>
>                 tok = strsep(&buf, ",");
>                 if (tok) {
> -                       strcpy(file_path, tok);
> +                       strscpy(file_path, tok);
>                 } else {
>                         ret = -EINVAL;
>                         goto out;
> --
> 2.46.2
>

Thanks
barry