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

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Date:   Mon, 17 Jul 2023 16:49:52 -0700
From:   Dan Williams <dan.j.williams@...el.com>
To:     Chenyuan Mi <michenyuan@...wei.com>, <dan.j.williams@...el.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()

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:

-- >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)