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Re: [libvirt] [PATCHv3 3/4] Simplify linuxNodeGetCPUStats



On 01/27/2014 05:16 PM, Eric Blake wrote:
> On 01/22/2014 06:37 AM, Ján Tomko wrote:
>> Split out the repetitive code.
>> ---
>>  src/nodeinfo.c | 77 +++++++++++++++++++++++-----------------------------------
>>  1 file changed, 30 insertions(+), 47 deletions(-)
>>
> 
> ACK.
> 
> 
>> @@ -722,51 +734,22 @@ linuxNodeGetCPUStats(FILE *procstat,
>>                  continue;
>>              }
>>  
>> -            for (i = 0; i < *nparams; i++) {
>> -                virNodeCPUStatsPtr param = &params[i];
> 
> The old loop terminates early if *nparams < 4.
> 

We can't get there with *nparams != 4:
     if ((*nparams) != LINUX_NB_CPU_STATS) {
         virReportInvalidArg(*nparams,
                             _("nparams in %s must be equal to %d"),
                             __FUNCTION__, LINUX_NB_CPU_STATS);
         goto cleanup;
     }

>> +            if (virNodeCPUStatsAssign(&params[0], VIR_NODE_CPU_STATS_KERNEL,
>> +                                      (sys + irq + softirq) * TICK_TO_NSEC) < 0)
>> +                goto cleanup;
>> +
>> +            if (virNodeCPUStatsAssign(&params[1], VIR_NODE_CPU_STATS_USER,
>> +                                      (usr + ni) * TICK_TO_NSEC) < 0)
>> +                goto cleanup;
>> +
>> +            if (virNodeCPUStatsAssign(&params[2], VIR_NODE_CPU_STATS_IDLE,
>> +                                      idle * TICK_TO_NSEC) < 0)
>> +                goto cleanup;
>> +
>> +            if (virNodeCPUStatsAssign(&params[3], VIR_NODE_CPU_STATS_IOWAIT,
>> +                                      iowait * TICK_TO_NSEC) < 0)
>> +                goto cleanup;
> 
> whereas the new code blindly dereferences past the end of the array.
> Needs another spin that avoids that issue.
> 

Jan

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