linux-kernel - Re: [PATCH] params: Replace deprecated strcpy() with strscpy()

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Message-ID: <f0a77c72-8fad-4fc5-9198-2a9c7c97a489@suse.com>
Date: Wed, 13 Aug 2025 13:42:39 +0200
From: Petr Pavlu <petr.pavlu@...e.com>
To: Thorsten Blum <thorsten.blum@...ux.dev>
Cc: Thomas Weißschuh <linux@...ssschuh.net>,
 Shyam Saini <shyamsaini@...ux.microsoft.com>,
 Luis Chamberlain <mcgrof@...nel.org>, Dmitry Antipov <dmantipov@...dex.ru>,
 linux-kernel@...r.kernel.org, linux-modules@...r.kernel.org
Subject: Re: [PATCH] params: Replace deprecated strcpy() with strscpy()

On 8/13/25 11:33 AM, Thorsten Blum wrote:
> Hi Petr,
> 
> On 13. Aug 2025, at 10:59, Petr Pavlu wrote:
>> Since the code already calculated the length of val and that it fits
>> into kps->string, is there any advantage (or disadvantage) to using
>> strscpy() over memcpy()?
> 
> strscpy() guarantees that the destination buffer 'kps->string' is always
> NUL-terminated, even if the source 'val' is not. memcpy() just copies
> the bytes as they are.
> 
> If it were guaranteed that 'val' is always NUL-terminated, memcpy()
> would be fine too, but since param_set_copystring() is exported, we
> probably can't make that assumption.

The function param_set_copystring() checks using
'strnlen(val, kps->maxlen) == kps->maxlen' if val contains NUL in the
first kps->maxlen bytes. It can use memcpy() instead of strscpy() to
avoid repeating this work.

-- Petr