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Date:   Sun, 12 Jun 2022 17:23:47 +0100
From:   Phillip Potter <phil@philpotter.co.uk>
To:     Bill Wendling <morbo@google.com>
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Subject: Re: [PATCH 08/12] cdrom: use correct format characters
Message-ID: <YqYTExy0IpVbunBL@equinox>
References: <20220609221702.347522-1-morbo@google.com>
 <20220609221702.347522-9-morbo@google.com>
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On Thu, Jun 09, 2022 at 10:16:27PM +0000, Bill Wendling wrote:
> From: Bill Wendling <isanbard@gmail.com>
> 
> When compiling with -Wformat, clang emits the following warnings:
> 
> drivers/cdrom/cdrom.c:3454:48: error: format string is not a string literal (potentially insecure) [-Werror,-Wformat-security]
>         ret = scnprintf(info + *pos, max_size - *pos, header);
>                                                       ^~~~~~
> 
> Use a string literal for the format string.
> 
> Link: https://github.com/ClangBuiltLinux/linux/issues/378
> Signed-off-by: Bill Wendling <isanbard@gmail.com>
> ---
>  drivers/cdrom/cdrom.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/cdrom/cdrom.c b/drivers/cdrom/cdrom.c
> index 416f723a2dbb..52b40120c76e 100644
> --- a/drivers/cdrom/cdrom.c
> +++ b/drivers/cdrom/cdrom.c
> @@ -3451,7 +3451,7 @@ static int cdrom_print_info(const char *header, int val, char *info,
>  	struct cdrom_device_info *cdi;
>  	int ret;
>  
> -	ret = scnprintf(info + *pos, max_size - *pos, header);
> +	ret = scnprintf(info + *pos, max_size - *pos, "%s", header);
>  	if (!ret)
>  		return 1;
>  
> -- 
> 2.36.1.255.ge46751e96f-goog
> 

Hi Bill,

Thank you for the patch, much appreciated.

Looking at this though, all callers of cdrom_print_info() provide 'header'
as a string literal defined within the driver, when making the call.
Therefore, I'm not convinced this change is necessary for cdrom.c -
that said, in this particular use case I don't think it would hurt
either.

I've followed the other responses on parts of this series, so I
understand that a different solution is potentially in the works.
Thought I'd respond anyway though out of courtesy.

All the best,
Phil (Uniform CDROM Maintainer)