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

Dmitry Osipenko
2021-03-24T19:50:40Z

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.