linux-kernel - RE: [PATCH] cxl: Fix memory leak bug in alloc_mock

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Date:   Mon, 17 Jul 2023 19:53:58 -0700
From:   Dan Williams <dan.j.williams@...el.com>
To:     Dan Williams <dan.j.williams@...el.com>,
        Chenyuan Mi <michenyuan@...wei.com>
CC:     <Jonathan.Cameron@...wei.com>, <dave.jiang@...el.com>,
        <rrichter@....com>, <alison.schofield@...el.com>,
        <linux-kernel@...r.kernel.org>, <linux-cxl@...r.kernel.org>
Subject: RE: [PATCH] cxl: Fix memory leak bug in alloc_mock_res()

Dan Williams wrote:
> Chenyuan Mi wrote:
> > When gen_pool_alloc_algo() fails, the error handling path
> > forgets to free 'res'. It would cause a memory leak bug.
> > 
> > Fix it by add kfree() in error handling path.
> 
> Going forward I want to set the policy that any error path resource leaks be
> fixed by converting to using __free() and associated helpers.
> 
> So in this case it would be:

...and to be clear I do think the fix should be applied in a backportable
fashion and then followed up with a conversion for the next merge window.

> 
> -- >8 --
> diff --git a/tools/testing/cxl/test/cxl.c b/tools/testing/cxl/test/cxl.c
> index 0e78d8e19895..ea04995fe42c 100644
> --- a/tools/testing/cxl/test/cxl.c
> +++ b/tools/testing/cxl/test/cxl.c
> @@ -396,7 +396,8 @@ static void depopulate_all_mock_resources(void)
>  
>  static struct cxl_mock_res *alloc_mock_res(resource_size_t size, int align)
>  {
> -	struct cxl_mock_res *res = kzalloc(sizeof(*res), GFP_KERNEL);
> +	struct cxl_mock_res *res __free(kfree) =
> +		kzalloc(sizeof(*res), GFP_KERNEL);
>  	struct genpool_data_align data = {
>  		.align = align,
>  	};
> @@ -416,7 +417,7 @@ static struct cxl_mock_res *alloc_mock_res(resource_size_t size, int align)
>  	list_add(&res->list, &mock_res);
>  	mutex_unlock(&mock_res_lock);
>  
> -	return res;
> +	return_ptr(res);
>  }
>  
>  static int populate_cedt(void)