linux-kernel - Re: [PATCH] cpumask: fix cpumask leak in partition_sched

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Message-ID: <87d2prqvse.fsf@rustcorp.com.au>
Date:	Tue, 06 Aug 2013 14:07:37 +0930
From:	Rusty Russell <rusty@...tcorp.com.au>
To:	Xiaotian Feng <xtfeng@...il.com>,
	Peter Zijlstra <peterz@...radead.org>
Cc:	Xiaotian Feng <xtfeng@...il.com>, Ingo Molnar <mingo@...hat.com>,
	linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] cpumask: fix cpumask leak in partition_sched_domains

Xiaotian Feng <xtfeng@...il.com> writes:
> On Sat, Jul 27, 2013 at 3:26 PM, Xiaotian Feng <xtfeng@...il.com> wrote:
>> If doms_new is NULL, partition_sched_domains() will reset ndoms_cur
>> to 0, and free old sched domains with free_sched_domains(doms_cur, ndoms_cur).
>> As ndoms_cur is 0, the cpumask will not be freed.
>>
>> Signed-off-by: Xiaotian Feng <xtfeng@...il.com>
>> Cc: Ingo Molnar <mingo@...hat.com>
>> Cc: Peter Zijlstra <peterz@...radead.org>
>> Cc: linux-kernel@...r.kernel.org
>
> Any comments? Cc'ed Rusty.

The code is a little convoluted, but your fix is logical.

>> ---
>>  kernel/sched/core.c |    5 +++--
>>  1 file changed, 3 insertions(+), 2 deletions(-)
>>
>> diff --git a/kernel/sched/core.c b/kernel/sched/core.c
>> index b7c32cb..3d6c57b 100644
>> --- a/kernel/sched/core.c
>> +++ b/kernel/sched/core.c
>> @@ -6184,8 +6184,9 @@ match1:
>>                 ;
>>         }
>>
>> +       n= ndoms_cur;

You're missing a ' ' here:
        n = ndoms_cur;

>>         if (doms_new == NULL) {
>> -               ndoms_cur = 0;
>> +               n = 0;
>>                 doms_new = &fallback_doms;
>>                 cpumask_andnot(doms_new[0], cpu_active_mask, cpu_isolated_map);
>>                 WARN_ON_ONCE(dattr_new);
>> @@ -6193,7 +6194,7 @@ match1:
>>
>>         /* Build new domains */
>>         for (i = 0; i < ndoms_new; i++) {
>> -               for (j = 0; j < ndoms_cur && !new_topology; j++) {
>> +               for (j = 0; j < n && !new_topology; j++) {
>>                         if (cpumask_equal(doms_new[i], doms_cur[j])
>>                             && dattrs_equal(dattr_new, i, dattr_cur, j))
>>                                 goto match2;
>> --
>> 1.7.9.6 (Apple Git-31.1)
>>

Cheers,
Rusty.
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