Re: [PATCH] hw/net/rocker: Avoid undefined shifts with more than 31 ports

[Richard Henderson <richard.henderson@linaro.org>]

On 8/4/22 03:45, Peter Maydell wrote:
> Ping?
> 
> thanks
> -- PMM
> 
> On Fri, 29 Jul 2022 at 16:59, Peter Maydell <peter.maydell@linaro.org> wrote:
>>
>> In rocker_port_phys_link_status() and rocker_port_phys_enable_read()
>> we construct a 64-bit value with one bit per front-panel port.
>> However we accidentally do the shift as 32-bit arithmetic, which
>> means that if there are more than 31 front-panel ports this is
>> undefined behaviour.
>>
>> Fix the problem by ensuring we use 64-bit arithmetic for the whole
>> calculation. (We won't ever shift off the 64-bit value because
>> ROCKER_FP_PORTS_MAX is 62.)
>>
>> Resolves: Coverity CID 1487121, 1487160
>> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>


r~

>> ---
>>   hw/net/rocker/rocker.c | 4 ++--
>>   1 file changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/hw/net/rocker/rocker.c b/hw/net/rocker/rocker.c
>> index 31f2340fb91..d8f3f16fe87 100644
>> --- a/hw/net/rocker/rocker.c
>> +++ b/hw/net/rocker/rocker.c
>> @@ -1010,7 +1010,7 @@ static uint64_t rocker_port_phys_link_status(Rocker *r)
>>           FpPort *port = r->fp_port[i];
>>
>>           if (fp_port_get_link_up(port)) {
>> -            status |= 1 << (i + 1);
>> +            status |= 1ULL << (i + 1);
>>           }
>>       }
>>       return status;
>> @@ -1025,7 +1025,7 @@ static uint64_t rocker_port_phys_enable_read(Rocker *r)
>>           FpPort *port = r->fp_port[i];
>>
>>           if (fp_port_enabled(port)) {
>> -            ret |= 1 << (i + 1);
>> +            ret |= 1ULL << (i + 1);
>>           }
>>       }
>>       return ret;
>