On 14/07/17 14:07, Arnd Bergmann wrote:
> gcc-7 notices that we copy a fixed length string into another
> string of the same size, with additional characters:
> 
> drivers/media/usb/usbvision/usbvision-i2c.c: In function 
> 'usbvision_i2c_register':
> drivers/media/usb/usbvision/usbvision-i2c.c:190:36: error: '%d' directive 
> writing between 1 and 11 bytes into a region of size between 0 and 47 
> [-Werror=format-overflow=]
>   sprintf(usbvision->i2c_adap.name, "%s-%d-%s", i2c_adap_template.name,
>                                     ^~~~~~~~~~
> drivers/media/usb/usbvision/usbvision-i2c.c:190:2: note: 'sprintf' output 
> between 4 and 76 bytes into a destination of size 48
> 
> We know this is fine as the template name is always "usbvision", so
> we can easily avoid the warning by using this as the format string
> directly.

Hmm, how about replacing sprintf by snprintf? That feels a lot safer (this is 
very
old code, it's not surprising it is still using sprintf).

Regards,

        Hans

> 
> Signed-off-by: Arnd Bergmann <a...@arndb.de>
> ---
>  drivers/media/usb/usbvision/usbvision-i2c.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/media/usb/usbvision/usbvision-i2c.c 
> b/drivers/media/usb/usbvision/usbvision-i2c.c
> index fdf6b6e285da..aae9f69884da 100644
> --- a/drivers/media/usb/usbvision/usbvision-i2c.c
> +++ b/drivers/media/usb/usbvision/usbvision-i2c.c
> @@ -187,8 +187,8 @@ int usbvision_i2c_register(struct usb_usbvision 
> *usbvision)
>  
>       usbvision->i2c_adap = i2c_adap_template;
>  
> -     sprintf(usbvision->i2c_adap.name, "%s-%d-%s", i2c_adap_template.name,
> -             usbvision->dev->bus->busnum, usbvision->dev->devpath);
> +     sprintf(usbvision->i2c_adap.name, "usbvision-%d-%s",
> +              usbvision->dev->bus->busnum, usbvision->dev->devpath);
>       PDEBUG(DBG_I2C, "Adaptername: %s", usbvision->i2c_adap.name);
>       usbvision->i2c_adap.dev.parent = &usbvision->dev->dev;
>  
> 

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