Re: [PATCH v2] mem: fix undefined behavior in NUMA code

["Burakov, Anatoly" <anatoly.burakov@intel.com>]

On 21-Sep-18 7:47 AM, Ilya Maximets wrote:
> On 20.09.2018 15:50, Anatoly Burakov wrote:
>> When NUMA-aware hugepages config option is set, we rely on
>> libnuma to tell the kernel to allocate hugepages on a specific
>> NUMA node. However, we allocate node mask before we check if
>> NUMA is available in the first place, which, according to
>> the manpage [1], causes undefined behaviour.
>>
>> Fix by only using nodemask when we have NUMA available.
>>
>> [1] https://linux.die.net/man/3/numa_alloc_onnode
>>
>> Bugzilla ID: 20
>>
>> Fixes: 1b72605d2416 ("mem: balanced allocation of hugepages")
>> Cc: i.maximets@samsung.com
>> Cc: stable@dpdk.org
>>
>> Signed-off-by: Anatoly Burakov <anatoly.burakov@intel.com>
>> ---
>>   lib/librte_eal/linuxapp/eal/eal_memory.c | 5 +++--
>>   1 file changed, 3 insertions(+), 2 deletions(-)
>>
>> diff --git a/lib/librte_eal/linuxapp/eal/eal_memory.c b/lib/librte_eal/linuxapp/eal/eal_memory.c
>> index dbf19499e..1a2a84a65 100644
>> --- a/lib/librte_eal/linuxapp/eal/eal_memory.c
>> +++ b/lib/librte_eal/linuxapp/eal/eal_memory.c
>> @@ -263,7 +263,7 @@ map_all_hugepages(struct hugepage_file *hugepg_tbl, struct hugepage_info *hpi,
>>   	int node_id = -1;
>>   	int essential_prev = 0;
>>   	int oldpolicy;
>> -	struct bitmask *oldmask = numa_allocate_nodemask();
>> +	struct bitmask *oldmask = NULL;
>>   	bool have_numa = true;
>>   	unsigned long maxnode = 0;
>>   
>> @@ -275,6 +275,7 @@ map_all_hugepages(struct hugepage_file *hugepg_tbl, struct hugepage_info *hpi,
>>   
>>   	if (have_numa) {
>>   		RTE_LOG(DEBUG, EAL, "Trying to obtain current memory policy.\n");
>> +		oldmask = numa_allocate_nodemask();
>>   		if (get_mempolicy(&oldpolicy, oldmask->maskp,
>>   				  oldmask->size + 1, 0, 0) < 0) {
>>   			RTE_LOG(ERR, EAL,
>> @@ -401,8 +402,8 @@ map_all_hugepages(struct hugepage_file *hugepg_tbl, struct hugepage_info *hpi,
>>   				strerror(errno));
>>   			numa_set_localalloc();
>>   		}
>> +		numa_free_cpumask(oldmask);
>>   	}
>> -	numa_free_cpumask(oldmask);
> 
> There will be 'oldmask' leak in case no 'socket-mem' requested.

Oh, right, you're correct!

> 
>>   #endif
>>   	return i;
>>   }
>>
> 


-- 
Thanks,
Anatoly