Re: [PATCH] mm: cma: fix corruption cma_sysfs_alloc_pages_count

Dmitry Osipenko
2021-03-24T20:03:45Z

24.03.2021 22:57, Minchan Kim пишет:
> On Wed, Mar 24, 2021 at 10:49:58PM +0300, Dmitry Osipenko wrote:
>> 24.03.2021 22:43, Dmitry Osipenko пишет:
>>> 24.03.2021 22:20, Minchan Kim пишет:
>>>> static int __init cma_sysfs_init(void)
>>>> {
>>>> - int i = 0;
>>>> + struct kobject *cma_kobj_root;
>>>> + struct cma_kobject *cma_kobj;
>>>> struct cma *cma;
>>>> + unsigned int i;
>>>
>>>> while (--i >= 0) {
>>>
>>> Do you realize that this doesn't work anymore?
>>>
>>>> cma = &cma_areas[i];
>>>> - kobject_put(&cma->stat->kobj);
>>>> - }
>>>>
>>>> - kfree(cma_stats);
>>>> - kobject_put(cma_kobj);
>>>> + kobject_put(&cma->cma_kobj->kobj);
>>>> + kfree(cma->cma_kobj);
>>>
>>> Freeing a null pointer?
>>>
>>>> + cma->cma_kobj = NULL;
>>>> + }
>>>> + kobject_put(cma_kobj_root);
>>>
>>
>> Please try to simulate the errors and check that error path is working
>> properly in the next version.
>>
>> Alternatively, we could remove the cma_kobj_release entirely, like Greg
>> suggested previously, and then don't care about cleaning up at all.
>
> Does he suggested it to remove cma_kobj_release?(Initially, I did but
> was rejected from Greg)
>

Alright, I haven't followed the previous threads fully and only saw the
reply where he suggested to removed it.