linux-kernel - Re: [PATCH 4/5] [v2] blktrace: convert strncpy() to strscpy

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Date: Wed, 10 Apr 2024 21:13:05 +0000
From: Justin Stitt <justinstitt@...gle.com>
To: Arnd Bergmann <arnd@...nel.org>
Cc: linux-kbuild@...r.kernel.org, Arnd Bergmann <arnd@...db.de>, 
	Richard Russon <ldm@...tcap.org>, Jens Axboe <axboe@...nel.dk>, 
	Robert Moore <robert.moore@...el.com>, "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>, 
	Len Brown <lenb@...nel.org>, Steven Rostedt <rostedt@...dmis.org>, 
	Masami Hiramatsu <mhiramat@...nel.org>, Mathieu Desnoyers <mathieu.desnoyers@...icios.com>, 
	Andrew Morton <akpm@...ux-foundation.org>, Masahiro Yamada <masahiroy@...nel.org>, 
	Nathan Chancellor <nathan@...nel.org>, Nicolas Schier <nicolas@...sle.eu>, 
	Lin Ming <ming.m.lin@...el.com>, Alexey Starikovskiy <astarikovskiy@...e.de>, 
	linux-ntfs-dev@...ts.sourceforge.net, linux-block@...r.kernel.org, linux-kernel@...r.kernel.org, 
	linux-acpi@...r.kernel.org, acpica-devel@...ts.linux.dev, linux-trace-kernel@...r.kernel.org
Subject: Re: [PATCH 4/5] [v2] blktrace: convert strncpy() to strscpy_pad()

Hi,

On Tue, Apr 09, 2024 at 04:00:57PM +0200, Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@...db.de>
> 
> gcc-9 warns about a possibly non-terminated string copy:
> 
> kernel/trace/blktrace.c: In function 'do_blk_trace_setup':
> kernel/trace/blktrace.c:527:2: error: 'strncpy' specified bound 32 equals destination size [-Werror=stringop-truncation]
> 
> Newer versions are fine here because they see the following explicit
> nul-termination. Using strscpy_pad() avoids the warning and
> simplifies the code a little. The padding helps  give a clean
> buffer to userspace.
> 
> Signed-off-by: Arnd Bergmann <arnd@...db.de>

Acked-by: Justin Stitt <justinstitt@...gle.com>

> ---
> v2: actually use padding version of strscpy.
> ---
>  kernel/trace/blktrace.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/kernel/trace/blktrace.c b/kernel/trace/blktrace.c
> index d5d94510afd3..8fd292d34d89 100644
> --- a/kernel/trace/blktrace.c
> +++ b/kernel/trace/blktrace.c
> @@ -524,8 +524,7 @@ static int do_blk_trace_setup(struct request_queue *q, char *name, dev_t dev,
>  	if (!buts->buf_size || !buts->buf_nr)
>  		return -EINVAL;
>  
> -	strncpy(buts->name, name, BLKTRACE_BDEV_SIZE);
> -	buts->name[BLKTRACE_BDEV_SIZE - 1] = '\0';
> +	strscpy_pad(buts->name, name, BLKTRACE_BDEV_SIZE);
>  
>  	/*
>  	 * some device names have larger paths - convert the slashes
> -- 
> 2.39.2
> 

Thanks
Justin