2021-09-09 05:29:32

by Xiyu Yang

Subject: [PATCH] kunit: fix reference count leak in kfree_at_end

The reference counting issue happens in the normal path of
kfree_at_end(). When kunit_alloc_and_get_resource() is invoked, the
function forgets to handle the returned resource object, whose refcount
increased inside, causing a refcount leak.

Fix this issue by calling kunit_put_resource() at the end of function.

Signed-off-by: Xiyu Yang <[email protected]>
Signed-off-by: Xin Tan <[email protected]>
---
lib/kunit/executor_test.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/lib/kunit/executor_test.c b/lib/kunit/executor_test.c
index cdbe54b16501..3af30abad826 100644
--- a/lib/kunit/executor_test.c
+++ b/lib/kunit/executor_test.c
@@ -113,11 +113,13 @@ static void kfree_res_free(struct kunit_resource *res)
*/
static void kfree_at_end(struct kunit *test, const void *to_free)
{
+ struct kunit_resource *res;
/* kfree() handles NULL already, but avoid allocating a no-op cleanup. */
if (IS_ERR_OR_NULL(to_free))
return;
- kunit_alloc_and_get_resource(test, NULL, kfree_res_free, GFP_KERNEL,
+ res = kunit_alloc_and_get_resource(test, NULL, kfree_res_free, GFP_KERNEL,
(void *)to_free);
+ kunit_put_resource(res);
}

static struct kunit_suite *alloc_fake_suite(struct kunit *test,
--
2.7.4

2021-09-09 06:59:04

by David Gow

Subject: Re: [PATCH] kunit: fix reference count leak in kfree_at_end

On Thu, Sep 9, 2021 at 1:28 PM 'Xiyu Yang' via KUnit Development
<[email protected]> wrote:
>
> The reference counting issue happens in the normal path of
> kfree_at_end(). When kunit_alloc_and_get_resource() is invoked, the
> function forgets to handle the returned resource object, whose refcount
> increased inside, causing a refcount leak.
>
> Fix this issue by calling kunit_put_resource() at the end of function.
>
> Signed-off-by: Xiyu Yang <[email protected]>
> Signed-off-by: Xin Tan <[email protected]>
> ---

Thanks for looking into this.

+ Daniel -- any thoughts?

> lib/kunit/executor_test.c | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/lib/kunit/executor_test.c b/lib/kunit/executor_test.c
> index cdbe54b16501..3af30abad826 100644
> --- a/lib/kunit/executor_test.c
> +++ b/lib/kunit/executor_test.c
> @@ -113,11 +113,13 @@ static void kfree_res_free(struct kunit_resource *res)
> */
> static void kfree_at_end(struct kunit *test, const void *to_free)
> {
> + struct kunit_resource *res;
> /* kfree() handles NULL already, but avoid allocating a no-op cleanup. */
> if (IS_ERR_OR_NULL(to_free))
> return;
> - kunit_alloc_and_get_resource(test, NULL, kfree_res_free, GFP_KERNEL,
> + res = kunit_alloc_and_get_resource(test, NULL, kfree_res_free, GFP_KERNEL,
> (void *)to_free);
> + kunit_put_resource(res);

Why not just change this to kunit_alloc_resource()?

> }
>
> static struct kunit_suite *alloc_fake_suite(struct kunit *test,
> --
> 2.7.4
>
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