linux-kernel - Re: [PATCH] mm: cma: fix corruption cma_sysfs_alloc_pages

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Date:   Wed, 24 Mar 2021 22:43:49 +0300
From:   Dmitry Osipenko <digetx@...il.com>
To:     Minchan Kim <minchan@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>
Cc:     linux-mm <linux-mm@...ck.org>, LKML <linux-kernel@...r.kernel.org>,
        gregkh@...uxfoundation.org, surenb@...gle.com, joaodias@...gle.com,
        jhubbard@...dia.com, willy@...radead.org
Subject: Re: [PATCH] mm: cma: fix corruption cma_sysfs_alloc_pages_count

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);