linux-kernel - Re: [PATCH] coccinelle: api: fix device_attr

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Message-ID: <3c266a0e-a2b9-ffde-0768-3b4fa89b0bfe@samsung.com>
Date:   Tue, 8 Sep 2020 13:37:08 +0200
From:   Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>
To:     kernel test robot <lkp@...el.com>
Cc:     Denis Efremov <efremov@...ux.com>, kbuild-all@...ts.01.org,
        linux-kernel@...r.kernel.org, Julia Lawall <Julia.Lawall@...6.fr>,
        Daniel Vetter <daniel.vetter@...ll.ch>,
        Nathan Chancellor <natechancellor@...il.com>,
        Sam Ravnborg <sam@...nborg.org>,
        Alex Deucher <alexander.deucher@....com>,
        Qiujun Huang <hqjagain@...il.com>,
        Peter Rosin <peda@...ntia.se>, dri-devel@...ts.freedesktop.org
Subject: Re: [PATCH] coccinelle: api: fix device_attr_show.cocci warnings


Hi,

On 8/10/20 11:21 AM, kernel test robot wrote:
> From: kernel test robot <lkp@...el.com>
> 
> drivers/video/fbdev/core/fbcon.c:3509:8-16: WARNING: use scnprintf or sprintf
> drivers/video/fbdev/core/fbcon.c:3484:8-16: WARNING: use scnprintf or sprintf
> 
> 
>  From Documentation/filesystems/sysfs.txt:
>   show() must not use snprintf() when formatting the value to be
>   returned to user space. If you can guarantee that an overflow
>   will never happen you can use sprintf() otherwise you must use
>   scnprintf().
> 
> Generated by: scripts/coccinelle/api/device_attr_show.cocci
> 
> Fixes: abfc19ff202d ("coccinelle: api: add device_attr_show script")
> CC: Denis Efremov <efremov@...ux.com>
> Signed-off-by: kernel test robot <lkp@...el.com>
> ---
> 
> tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
> head:   fc80c51fd4b23ec007e88d4c688f2cac1b8648e7
> commit: abfc19ff202d287742483e15fd478ddd6ada2187 coccinelle: api: add device_attr_show script
> 
> Please take the patch only if it's a positive warning. Thanks!
> 
>  fbcon.c |    4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> --- a/drivers/video/fbdev/core/fbcon.c
> +++ b/drivers/video/fbdev/core/fbcon.c
> @@ -3481,7 +3481,7 @@ static ssize_t show_rotate(struct device
>  	rotate = fbcon_get_rotate(info);
>  err:
>  	console_unlock();
> -	return snprintf(buf, PAGE_SIZE, "%d\n", rotate);
> +	return scnprintf(buf, PAGE_SIZE, "%d\n", rotate);

buf length is at least PAGE_SIZE and rotate val is an int so
shouldn't this be converted to use sprintf() instead?

>  }
>  
>  static ssize_t show_cursor_blink(struct device *device,
> @@ -3506,7 +3506,7 @@ static ssize_t show_cursor_blink(struct
>  	blink = (ops->flags & FBCON_FLAGS_CURSOR_TIMER) ? 1 : 0;
>  err:
>  	console_unlock();
> -	return snprintf(buf, PAGE_SIZE, "%d\n", blink);
> +	return scnprintf(buf, PAGE_SIZE, "%d\n", blink);

ditto for blink val

>  }
>  
>  static ssize_t store_cursor_blink(struct device *device,
> 
 
Best regards,
--
Bartlomiej Zolnierkiewicz
Samsung R&D Institute Poland
Samsung Electronics