linux-kernel - Re: [PATCH v6 RESEND] dma-buf: system_heap: Add a size check for allocation

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Message-ID: <90bf495d-dbf6-cb0d-f54f-e0080b810f8d@amd.com>
Date:   Thu, 20 Jan 2022 11:22:10 +0100
From:   Christian König <christian.koenig@....com>
To:     guangming.cao@...iatek.com
Cc:     benjamin.gaignard@...aro.org, bo.song@...iatek.com,
        caoguangming34@...il.com, dri-devel@...ts.freedesktop.org,
        jianjiao.zeng@...iatek.com, john.stultz@...aro.org,
        labbott@...hat.com, libo.kang@...iatek.com,
        linaro-mm-sig@...ts.linaro.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-media@...r.kernel.org, linux-mediatek@...ts.infradead.org,
        lmark@...eaurora.org, matthias.bgg@...il.com,
        michael.j.ruhl@...el.com, mingyuan.ma@...iatek.com,
        sumit.semwal@...aro.org, wsd_upstream@...iatek.com,
        yf.wang@...iatek.com
Subject: Re: [PATCH v6 RESEND] dma-buf: system_heap: Add a size check for
 allocation

Am 20.01.22 um 11:00 schrieb guangming.cao@...iatek.com:
> From: Guangming <Guangming.Cao@...iatek.com>
>
> Add a size check for allocation since the allocation size should be
> always less than the total DRAM size on system heap.
> Adding this check can prevent comsuming too much time for invalid allocations.
>
> Signed-off-by: Guangming <Guangming.Cao@...iatek.com>
> Acked-by: John Stultz <john.stultz@...aro.org>

Acked-by: Christian König <christian.koenig@....com>

> ---
>   drivers/dma-buf/heaps/system_heap.c | 8 ++++++++
>   1 file changed, 8 insertions(+)
>
> diff --git a/drivers/dma-buf/heaps/system_heap.c b/drivers/dma-buf/heaps/system_heap.c
> index 23a7e74ef966..b65e597a742f 100644
> --- a/drivers/dma-buf/heaps/system_heap.c
> +++ b/drivers/dma-buf/heaps/system_heap.c
> @@ -347,6 +347,14 @@ static struct dma_buf *system_heap_allocate(struct dma_heap *heap,
>   	struct page *page, *tmp_page;
>   	int i, ret = -ENOMEM;
>   
> +	/*
> +	 * Size check. The "len" should be less than totalram since system_heap
> +	 * memory is comes from system. Adding check here can prevent comsuming
> +	 * too much time for invalid allocations.
> +	 */
> +	if (PFN_DOWN(len) > totalram_pages())
> +		return ERR_PTR(-EINVAL);
> +
>   	buffer = kzalloc(sizeof(*buffer), GFP_KERNEL);
>   	if (!buffer)
>   		return ERR_PTR(-ENOMEM);