linux-kernel - Re: [PATCH] coresight: tmc-etr: Check if page is valid before dma_map

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Date:   Mon, 23 Nov 2020 10:46:56 +0000
From:   Suzuki K Poulose <suzuki.poulose@....com>
To:     Sai Prakash Ranjan <saiprakash.ranjan@...eaurora.org>,
        Mathieu Poirier <mathieu.poirier@...aro.org>,
        Mike Leach <mike.leach@...aro.org>
Cc:     coresight@...ts.linaro.org, Stephen Boyd <swboyd@...omium.org>,
        linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        Mao Jinlong <jinlmao@...eaurora.org>, stable@...r.kernel.org
Subject: Re: [PATCH] coresight: tmc-etr: Check if page is valid before
 dma_map_page()

On 11/23/20 10:21 AM, Sai Prakash Ranjan wrote:
> From: Mao Jinlong <jinlmao@...eaurora.org>
> 
> alloc_pages_node() return should be checked before calling
> dma_map_page() to make sure that valid page is mapped or
> else it can lead to aborts as below:
> 
>   Unable to handle kernel paging request at virtual address ffffffc008000000
>   Mem abort info:
>   <snip>...
>   pc : __dma_inv_area+0x40/0x58
>   lr : dma_direct_map_page+0xd8/0x1c8
> 
>   Call trace:
>    __dma_inv_area
>    tmc_pages_alloc
>    tmc_alloc_data_pages
>    tmc_alloc_sg_table
>    tmc_init_etr_sg_table
>    tmc_alloc_etr_buf
>    tmc_enable_etr_sink_sysfs
>    tmc_enable_etr_sink
>    coresight_enable_path
>    coresight_enable
>    enable_source_store
>    dev_attr_store
>    sysfs_kf_write
> 
> Fixes: 99443ea19e8b ("coresight: Add generic TMC sg table framework")
> Cc: stable@...r.kernel.org
> Signed-off-by: Mao Jinlong <jinlmao@...eaurora.org>
> Signed-off-by: Sai Prakash Ranjan <saiprakash.ranjan@...eaurora.org>

Reviewed-by: Suzuki K Poulose <suzuki.poulose@....com>

> ---
>   drivers/hwtracing/coresight/coresight-tmc-etr.c | 2 ++
>   1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/hwtracing/coresight/coresight-tmc-etr.c b/drivers/hwtracing/coresight/coresight-tmc-etr.c
> index 525f0ecc129c..a31a4d7ae25e 100644
> --- a/drivers/hwtracing/coresight/coresight-tmc-etr.c
> +++ b/drivers/hwtracing/coresight/coresight-tmc-etr.c
> @@ -217,6 +217,8 @@ static int tmc_pages_alloc(struct tmc_pages *tmc_pages,
>   		} else {
>   			page = alloc_pages_node(node,
>   						GFP_KERNEL | __GFP_ZERO, 0);
> +			if (!page)
> +				goto err;
>   		}
>   		paddr = dma_map_page(real_dev, page, 0, PAGE_SIZE, dir);
>   		if (dma_mapping_error(real_dev, paddr))
> 
> base-commit: c04e5d7bbf6f92a346d6b36770705e7f034df42d
>