ALSA: xen-front: fix unintention integer overflow on left shifts

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

Posted by Colin King 4 years, 10 months ago

From: Colin Ian King <colin.king@canonical.com>

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@canonical.com>
---
 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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Re: [Xen-devel] [PATCH] ALSA: xen-front: fix unintention integer overflow on left shifts

Posted by Takashi Iwai 4 years, 10 months ago

On Thu, 27 Jun 2019 18:58:53 +0200,
Colin King wrote:
> 
> From: Colin Ian King <colin.king@canonical.com>
> 
> 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@canonical.com>

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

Posted by Oleksandr Andrushchenko 4 years, 9 months ago

On 6/28/19 11:46 AM, Takashi Iwai wrote:
> On Thu, 27 Jun 2019 18:58:53 +0200,
> Colin King wrote:
>> From: Colin Ian King <colin.king@canonical.com>
>>
>> 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@canonical.com>
Thank you for you patch,
Oleksandr
> 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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