linux-kernel - Re: [PATCH v3] dma-buf/heaps: system

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <ZDZqYTSHBNGLq0zI@dhcp22.suse.cz>
Date:   Wed, 12 Apr 2023 10:22:57 +0200
From:   Michal Hocko <mhocko@...e.com>
To:     Jaewon Kim <jaewon31.kim@...sung.com>
Cc:     jstultz@...gle.com, tjmercier@...gle.com, sumit.semwal@...aro.org,
        daniel.vetter@...ll.ch, akpm@...ux-foundation.org,
        hannes@...xchg.org, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org, jaewon31.kim@...il.com
Subject: Re: [PATCH v3] dma-buf/heaps: system_heap: avoid too much allocation

Sorry for being late. I know there was some pre-existing discussion
around that but I didn't have time to participate.

On Mon 10-04-23 16:32:28, Jaewon Kim wrote:
> @@ -350,6 +350,9 @@ static struct dma_buf *system_heap_allocate(struct dma_heap *heap,
>  	struct page *page, *tmp_page;
>  	int i, ret = -ENOMEM;
>  
> +	if (len / PAGE_SIZE > totalram_pages())
> +		return ERR_PTR(-ENOMEM);
> +

This is an antipattern imho. Check 7661809d493b ("mm: don't allow
oversized kvmalloc() calls") how kvmalloc has dealt with a similar
issue. totalram_pages doesn't really tell you anything about incorrect
users. You might be on a low memory system where the request size is
sane normally, it just doesn't fit into memory on that particular
machine.

>  	buffer = kzalloc(sizeof(*buffer), GFP_KERNEL);
>  	if (!buffer)
>  		return ERR_PTR(-ENOMEM);
> -- 
> 2.17.1

-- 
Michal Hocko
SUSE Labs