linux-kernel - Re: [PATCH] ACPI: scan: Fix DMA range assignment

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Date:   Wed, 19 Oct 2022 10:07:33 +0800
From:   Yicong Yang <yangyicong@...wei.com>
To:     Robin Murphy <robin.murphy@....com>, <rafael@...nel.org>
CC:     <yangyicong@...ilicon.com>, <lvjianmin@...ngson.cn>,
        <lpieralisi@...nel.org>, <chenhuacai@...ngson.cn>,
        <linux-acpi@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <lenb@...nel.org>, <jeremy.linton@....com>
Subject: Re: [PATCH] ACPI: scan: Fix DMA range assignment

On 2022/10/18 21:14, Robin Murphy wrote:
> Assigning the device's dma_range_map from the iterator variable after
> the loop means it always points to the empty terminator at the end of
> the map, which is not what we want. Similarly, freeing the iterator on
> error when it points to somwhere in the middle of the allocated array
> won't work either. Fix this.
> 
> Fixes: bf2ee8d0c385 ("ACPI: scan: Support multiple DMA windows with different offsets")

Thanks for fixing this. Works on my platform.

Tested-by: Yicong Yang <yangyicong@...ilicon.com>

> Signed-off-by: Robin Murphy <robin.murphy@....com>
> ---
>  drivers/acpi/scan.c | 7 ++++---
>  1 file changed, 4 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
> index 558664d169fc..024cc373a197 100644
> --- a/drivers/acpi/scan.c
> +++ b/drivers/acpi/scan.c
> @@ -1509,9 +1509,12 @@ int acpi_dma_get_range(struct device *dev, const struct bus_dma_region **map)
>  			goto out;
>  		}
>  
> +		*map = r;
> +
>  		list_for_each_entry(rentry, &list, node) {
>  			if (rentry->res->start >= rentry->res->end) {
> -				kfree(r);
> +				kfree(*map);
> +				*map = NULL;
>  				ret = -EINVAL;
>  				dev_dbg(dma_dev, "Invalid DMA regions configuration\n");
>  				goto out;
> @@ -1523,8 +1526,6 @@ int acpi_dma_get_range(struct device *dev, const struct bus_dma_region **map)
>  			r->offset = rentry->offset;
>  			r++;
>  		}
> -
> -		*map = r;
>  	}
>   out:
>  	acpi_dev_free_resource_list(&list);
>