Re: [PATCH] linux: sysconf: limit _SC_MAX_ARG to 6 MiB [BZ #25305]

[Michal Nazarewicz <mina86@mina86.com>]

> On 07/04/2021 12:10, Michal Nazarewicz wrote:
>> Since Linux 4.13, kernel limits the maximum command line arguments
>> length to 6 MiB.¹  Normally the limit is still quarter of the maximum
>> stack size but if that limit exceeds 6 MiB it’s clamped down.

On Mon, Apr 12 2021, Adhemerval Zanella wrote:
> Patch look good to me, thanks.
>
> Reviewed=by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>
>
>> ---
>>  sysdeps/unix/sysv/linux/sysconf.c | 5 ++++-
>>  1 file changed, 4 insertions(+), 1 deletion(-)
>> 
>> diff --git a/sysdeps/unix/sysv/linux/sysconf.c b/sysdeps/unix/sysv/linux/sysconf.c
>> index 366fcef01e..bd711795c7 100644
>> --- a/sysdeps/unix/sysv/linux/sysconf.c
>> +++ b/sysdeps/unix/sysv/linux/sysconf.c
>> @@ -55,7 +55,10 @@ __sysconf (int name)
>>          struct rlimit rlimit;
>>          /* Use getrlimit to get the stack limit.  */
>>          if (__getrlimit (RLIMIT_STACK, &rlimit) == 0)
>> -	  return MAX (legacy_ARG_MAX, rlimit.rlim_cur / 4);
>> +	  {
>> +	    const long int limit = MAX (legacy_ARG_MAX, rlimit.rlim_cur / 4);
>> +	    return MIN (limit, 6 << 10 << 10);
>
> I think it a bit easier to read with the value expanded (6291456).

I’d rather go with ‘6 * 1024 * 1024’ if shifts aren’t readable.

>> +	  }
>>  
>>          return legacy_ARG_MAX;
>>        }
>> 

-- 
Best regards
ミハウ “𝓶𝓲𝓷𝓪86” ナザレヴイツ
«If at first you don’t succeed, give up skydiving»