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

Minchan Kim
2021-03-24T19:58:23Z

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)