[PATCH][next] seg6: fix unintentional integer overflow on left shift

[PATCH][next] seg6: fix unintentional integer overflow on left shift

[Colin King]

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 unsigned long value
leads to a potential integer overflow. Fix this by using the BIT
macro to perform the shift to avoid the overflow.

Addresses-Coverity: ("Uninitentional integer overflow")
Fixes: 964adce526a4 ("seg6: improve management of behavior attributes")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
---
 net/ipv6/seg6_local.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/ipv6/seg6_local.c b/net/ipv6/seg6_local.c
index b07f7c1c82a4..d68de8cd1207 100644
--- a/net/ipv6/seg6_local.c
+++ b/net/ipv6/seg6_local.c
@@ -1366,7 +1366,7 @@ static void __destroy_attrs(unsigned long parsed_attrs, int max_parsed,
 	 * attribute; otherwise, we call the destroy() callback.
 	 */
 	for (i = 0; i < max_parsed; ++i) {
-		if (!(parsed_attrs & (1 << i)))
+		if (!(parsed_attrs & BIT(i)))
 			continue;
 
 		param = &seg6_action_params[i];
-- 
2.29.2

Re: [PATCH][next] seg6: fix unintentional integer overflow on left shift

[Andrea Mayer]

On Mon,  7 Dec 2020 14:45:03 +0000
Colin King <colin.king@canonical.com> 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 unsigned long value
> leads to a potential integer overflow. Fix this by using the BIT
> macro to perform the shift to avoid the overflow.
> 
> Addresses-Coverity: ("Uninitentional integer overflow")
> Fixes: 964adce526a4 ("seg6: improve management of behavior attributes")
> Signed-off-by: Colin Ian King <colin.king@canonical.com>
> ---
>  net/ipv6/seg6_local.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/net/ipv6/seg6_local.c b/net/ipv6/seg6_local.c
> index b07f7c1c82a4..d68de8cd1207 100644
> --- a/net/ipv6/seg6_local.c
> +++ b/net/ipv6/seg6_local.c
> @@ -1366,7 +1366,7 @@ static void __destroy_attrs(unsigned long parsed_attrs, int max_parsed,
>  	 * attribute; otherwise, we call the destroy() callback.
>  	 */
>  	for (i = 0; i < max_parsed; ++i) {
> -		if (!(parsed_attrs & (1 << i)))
> +		if (!(parsed_attrs & BIT(i)))
>  			continue;
>  
>  		param = &seg6_action_params[i];
> -- 
> 2.29.2
>

Hi Colin,
thanks for the fix. I've just given a look a the whole seg6_local.c code and I
found that such issues is present in other parts of the code.

If we agree, I can make a fix which explicitly eliminates the several (1 << i)
in favor of BIT(i).

Andrea

Re: [PATCH][next] seg6: fix unintentional integer overflow on left shift

[Colin Ian King]

On 07/12/2020 19:59, Andrea Mayer wrote:
> On Mon,  7 Dec 2020 14:45:03 +0000
> Colin King <colin.king@canonical.com> 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 unsigned long value
>> leads to a potential integer overflow. Fix this by using the BIT
>> macro to perform the shift to avoid the overflow.
>>
>> Addresses-Coverity: ("Uninitentional integer overflow")
>> Fixes: 964adce526a4 ("seg6: improve management of behavior attributes")
>> Signed-off-by: Colin Ian King <colin.king@canonical.com>
>> ---
>>  net/ipv6/seg6_local.c | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/net/ipv6/seg6_local.c b/net/ipv6/seg6_local.c
>> index b07f7c1c82a4..d68de8cd1207 100644
>> --- a/net/ipv6/seg6_local.c
>> +++ b/net/ipv6/seg6_local.c
>> @@ -1366,7 +1366,7 @@ static void __destroy_attrs(unsigned long parsed_attrs, int max_parsed,
>>  	 * attribute; otherwise, we call the destroy() callback.
>>  	 */
>>  	for (i = 0; i < max_parsed; ++i) {
>> -		if (!(parsed_attrs & (1 << i)))
>> +		if (!(parsed_attrs & BIT(i)))
>>  			continue;
>>  
>>  		param = &seg6_action_params[i];
>> -- 
>> 2.29.2
>>
> 
> Hi Colin,
> thanks for the fix. I've just given a look a the whole seg6_local.c code and I
> found that such issues is present in other parts of the code.
> 
> If we agree, I can make a fix which explicitly eliminates the several (1 << i)
> in favor of BIT(i).

Sounds good to me.

Colin

> 
> Andrea
>