Re: [Xen-devel] [PATCH] ALSA: xen-front: fix unintention integer overflow on left shifts

[Takashi Iwai <tiwai@xxxxxxx>]

On Thu, 27 Jun 2019 18:58:53 +0200,
Colin King wrote:
> 
> From: Colin Ian King <colin.king@xxxxxxxxxxxxx>
> 
> Shifting the integer value 1 is evaluated using 32-bit
> arithmetic and then used in an expression that expects a 64-bit
> value, so there is potentially an integer overflow. Fix this
> by using the BIT_ULL macro to perform the shift.
> 
> Addresses-Coverity: ("Unintentional integer overflow")
> Signed-off-by: Colin Ian King <colin.king@xxxxxxxxxxxxx>

The fix is correct, but luckily we didn't hit the integer overflow, as
all passed values are less than 32bit.

In anyway, applied now.  Thanks.


Takashi

> ---
>  sound/xen/xen_snd_front_alsa.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/sound/xen/xen_snd_front_alsa.c b/sound/xen/xen_snd_front_alsa.c
> index b14ab512c2ce..e01631959ed8 100644
> --- a/sound/xen/xen_snd_front_alsa.c
> +++ b/sound/xen/xen_snd_front_alsa.c
> @@ -196,7 +196,7 @@ static u64 to_sndif_formats_mask(u64 alsa_formats)
>       mask = 0;
>       for (i = 0; i < ARRAY_SIZE(ALSA_SNDIF_FORMATS); i++)
>               if (pcm_format_to_bits(ALSA_SNDIF_FORMATS[i].alsa) & 
> alsa_formats)
> -                     mask |= 1 << ALSA_SNDIF_FORMATS[i].sndif;
> +                     mask |= BIT_ULL(ALSA_SNDIF_FORMATS[i].sndif);
>  
>       return mask;
>  }
> @@ -208,7 +208,7 @@ static u64 to_alsa_formats_mask(u64 sndif_formats)
>  
>       mask = 0;
>       for (i = 0; i < ARRAY_SIZE(ALSA_SNDIF_FORMATS); i++)
> -             if (1 << ALSA_SNDIF_FORMATS[i].sndif & sndif_formats)
> +             if (BIT_ULL(ALSA_SNDIF_FORMATS[i].sndif) & sndif_formats)
>                       mask |= pcm_format_to_bits(ALSA_SNDIF_FORMATS[i].alsa);
>  
>       return mask;
> -- 
> 2.20.1
> 
> 

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