linux-kernel - Re: [PATCH] tracing/synthetic: Replace deprecated strncpy() with strscpy()

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Message-ID: <20250311083701.6947bd0d@batman.local.home>
Date: Tue, 11 Mar 2025 08:37:01 -0400
From: Steven Rostedt <rostedt@...dmis.org>
To: Thorsten Blum <thorsten.blum@...ux.dev>
Cc: Masami Hiramatsu <mhiramat@...nel.org>, Mathieu Desnoyers
 <mathieu.desnoyers@...icios.com>, linux-hardening@...r.kernel.org,
 linux-kernel@...r.kernel.org, linux-trace-kernel@...r.kernel.org
Subject: Re: [PATCH] tracing/synthetic: Replace deprecated strncpy() with
 strscpy()

On Mon, 10 Mar 2025 21:03:58 +0100
Thorsten Blum <thorsten.blum@...ux.dev> wrote:

> diff --git a/kernel/trace/trace_events_synth.c b/kernel/trace/trace_events_synth.c
> index e3f7d09e5512..4b51f74897b4 100644
> --- a/kernel/trace/trace_events_synth.c
> +++ b/kernel/trace/trace_events_synth.c
> @@ -207,8 +207,7 @@ static int synth_field_string_size(char *type)
>  	if (len == 0)
>  		return 0; /* variable-length string */
>  
> -	strncpy(buf, start, len);
> -	buf[len] = '\0';
> +	strscpy(buf, start, len + 1);
>  
>  	err = kstrtouint(buf, 0, &size);
>  	if (err)
> -

Looking at the code, it calculates the start and end by scanning the
string. I think it's better to just use memcpy() instead. It's not like
it's copying a random string passed in.

-- Steve