Re: [PATCH 02/11] ALSA: usb-audio: Fix undefined behavior due to shift overflowing the constant

[Takashi Iwai]

On Tue, 05 Apr 2022 17:15:08 +0200,
Borislav Petkov wrote:
> 
> From: Borislav Petkov <bp@xxxxxxx>
> 
> Fix:
> 
>   sound/usb/midi.c: In function ‘snd_usbmidi_out_endpoint_create’:
>   sound/usb/midi.c:1389:2: error: case label does not reduce to an integer constant
>     case USB_ID(0xfc08, 0x0101): /* Unknown vendor Cable */
>     ^~~~
> 
> See https://lore.kernel.org/r/YkwQ6%2BtIH8GQpuct@xxxxxxx for the gory
> details as to why it triggers with older gccs only.
> 
> Signed-off-by: Borislav Petkov <bp@xxxxxxx>
> Cc: Jaroslav Kysela <perex@xxxxxxxx>
> Cc: Takashi Iwai <tiwai@xxxxxxxx>
> Cc: alsa-devel@xxxxxxxxxxxxxxxx
> ---
>  sound/usb/usbaudio.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/sound/usb/usbaudio.h b/sound/usb/usbaudio.h
> index 167834133b9b..2b3dd55e8ee0 100644
> --- a/sound/usb/usbaudio.h
> +++ b/sound/usb/usbaudio.h
> @@ -8,7 +8,7 @@
>   */
>  
>  /* handling of USB vendor/product ID pairs as 32-bit numbers */
> -#define USB_ID(vendor, product) (((vendor) << 16) | (product))
> +#define USB_ID(vendor, product) ((((unsigned int)vendor) << 16) | (product))

Parentheses are needed around vendor (as usual for a macro).
Could you resubmit with it?


Thanks.

Takashi