* [PATCH] peci: fix potential memory leak in devm_adev_add()
@ 2022-07-04 12:59 Jianglei Nie
2022-07-05 10:18 ` Winiarska, Iwona
0 siblings, 1 reply; 2+ messages in thread
From: Jianglei Nie @ 2022-07-04 12:59 UTC (permalink / raw)
To: iwona.winiarska; +Cc: openbmc, linux-kernel, Jianglei Nie
devm_adev_add() allocates a memory chunk for "adev" and "adev->name"
with adev_alloc(). When auxiliary_device_add() fails, the function calls
auxiliary_device_uninit(), which doesn't release the allocated "adev"
and "adev->name", thus leading to a memory leak bug.
We should call adev_release() instead of auxiliary_device_uninit() to
release the "adev" and "adev->name".
Signed-off-by: Jianglei Nie <niejianglei2021@163.com>
---
drivers/peci/cpu.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/peci/cpu.c b/drivers/peci/cpu.c
index 68eb61c65d34..de865997ccde 100644
--- a/drivers/peci/cpu.c
+++ b/drivers/peci/cpu.c
@@ -248,7 +248,7 @@ static int devm_adev_add(struct device *dev, int idx)
ret = auxiliary_device_add(adev);
if (ret) {
- auxiliary_device_uninit(adev);
+ adev_release(&adev->dev);
return ret;
}
--
2.25.1
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] peci: fix potential memory leak in devm_adev_add()
2022-07-04 12:59 [PATCH] peci: fix potential memory leak in devm_adev_add() Jianglei Nie
@ 2022-07-05 10:18 ` Winiarska, Iwona
0 siblings, 0 replies; 2+ messages in thread
From: Winiarska, Iwona @ 2022-07-05 10:18 UTC (permalink / raw)
To: niejianglei2021; +Cc: openbmc, linux-kernel
On Mon, 2022-07-04 at 20:59 +0800, Jianglei Nie wrote:
> devm_adev_add() allocates a memory chunk for "adev" and "adev->name"
> with adev_alloc(). When auxiliary_device_add() fails, the function calls
> auxiliary_device_uninit(), which doesn't release the allocated "adev"
> and "adev->name", thus leading to a memory leak bug.
>
> We should call adev_release() instead of auxiliary_device_uninit() to
> release the "adev" and "adev->name".
>
> Signed-off-by: Jianglei Nie <niejianglei2021@163.com>
> ---
> drivers/peci/cpu.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/peci/cpu.c b/drivers/peci/cpu.c
> index 68eb61c65d34..de865997ccde 100644
> --- a/drivers/peci/cpu.c
> +++ b/drivers/peci/cpu.c
> @@ -248,7 +248,7 @@ static int devm_adev_add(struct device *dev, int idx)
>
> ret = auxiliary_device_add(adev);
> if (ret) {
> - auxiliary_device_uninit(adev);
> + adev_release(&adev->dev);
> return ret;
> }
>
When we call auxiliary_device_uninit() the .release callback (adev_release())
will be triggered, so there's no memory leak here.
But thank you for pointing to this - it made me realize that we have a bug in
adev_release(), because we call auxiliary_device_uninit() there, which will
cause a use-after-free with refcount underflow in this case.
I'd appreciate if you could review it:
https://lore.kernel.org/lkml/20220705101501.298395-1-iwona.winiarska@intel.com/
Thanks
-Iwona
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