[PATCH] Fix range check in do_tunable_update_val

[Carlos O'Donell]

On 09/26/2017 12:54 PM, Siddhesh Poyarekar wrote:
> On Wednesday 27 September 2017 12:08 AM, Alexey Makhalov wrote:
>> Current implementation of tunables does not set arena_max and arena_test
>> values. Any value provided by glibc.malloc.arena_max and
>> glibc.malloc.arena_test parameters is ignored.
>>
>> These tunables have minval value set to 1 (see elf/dl-tunables.list file)
>> and undefined maxval value. In that case default value (which is 0. see
>> scripts/gen-tunables.awk) is being used to set maxval.
>>
>> For instance, generated tunable_list[] entry for arena_max is:
>> (gdb) p *cur
>> $1 = {name = 0x7ffff7df6217 "glibc.malloc.arena_max",
>>  type = {type_code = TUNABLE_TYPE_SIZE_T, min = 1, max = 0},
>>   val = {numval = 0, strval = 0x0}, initialized = false,
>>    security_level = TUNABLE_SECLEVEL_SXID_IGNORE,
>>     env_alias = 0x7ffff7df622e "MALLOC_ARENA_MAX"}
>>
>> As a result, any value of glibc.malloc.arena_max is ignored by
>> TUNABLE_SET_VAL_IF_VALID_RANGE macro
>>   __type min = (__cur)->type.min;                    <- initialized to 1
>>   __type max = (__cur)->type.max;                    <- initialized to 0!
>>   if (min == max)                                    <- false
>>     {
>>       min = __default_min;
>>       max = __default_max;
>>     }
>>   if ((__type) (__val) >= min && (__type) (val) <= max)  <- false
>>     {
>>       (__cur)->val.numval = val;
>>       (__cur)->initialized = true;
>>     }
>>
>> Assigning correct min/max values at a build time fixes a problem.
>> Plus, a bit of optimization: Setting of default min/max values for the
>> given type at a run time might be eliminated.
> 
> Thanks for the patch.  Can you please clarify the status of your
> copyright assignment (and Carlos verify it please)?  I don't have access
> to the copyright assignment list, so once that question is cleared, I'll
> test and merge this patch.

Both Alexey and VMWare for Alexey have assignments in place.

We can accept any patches from Alexey.

Cheers,
Carlos.



-- 
Cheers,
Carlos.