Re: [PATCH] staging: rtl8712: Replace snprintf with scnprintf

[Dan Carpenter <dan.carpenter@oracle.com>]

On Wed, Sep 11, 2019 at 12:19:31AM +0530, Rohit Sarkar wrote:
> When the number of bytes to be printed exceeds the limit snprintf
> returns the number of bytes that would have been printed (if there was
> no truncation). This might cause issues, hence use scnprintf which
                  ^^^^^^^^^^^^^^^^^^^^^^^
Nope.  The code handles that situation fine so it will not cause issues.

> returns the actual number of bytes printed to buffer always.
> 
> Signed-off-by: Rohit Sarkar <rohitsarkar5398@gmail.com>
> ---
>  drivers/staging/rtl8712/rtl871x_ioctl_linux.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/staging/rtl8712/rtl871x_ioctl_linux.c b/drivers/staging/rtl8712/rtl871x_ioctl_linux.c
> index b08b9a191a34..ff5edcaba64d 100644
> --- a/drivers/staging/rtl8712/rtl871x_ioctl_linux.c
> +++ b/drivers/staging/rtl8712/rtl871x_ioctl_linux.c
> @@ -142,7 +142,7 @@ static noinline_for_stack char *translate_scan_wpa(struct iw_request_info *info,
>  		memset(buf, 0, MAX_WPA_IE_LEN);
>  		n = sprintf(buf, "wpa_ie=");
>  		for (i = 0; i < wpa_len; i++) {
> -			n += snprintf(buf + n, MAX_WPA_IE_LEN - n,
> +			n += scnprintf(buf + n, MAX_WPA_IE_LEN - n,
>  						"%02x", wpa_ie[i]);
>  			if (n >= MAX_WPA_IE_LEN)
                            ^^^^^^^^^^^^^^^^^^^
It checks for overflow here.  This check is impossible now and doesn't
make sense.  The other loop is similar.

>  				break;

regards,
dan carpenter

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