Re: [PATCH v2] hid: logitech: check the return value of create_singlethread_workqueue

From: Jonathan Corbet
Date: Tue Mar 12 2019 - 12:02:38 EST


On Tue, 12 Mar 2019 01:16:28 -0500
Kangjie Lu <kjlu@xxxxxxx> wrote:

> create_singlethread_workqueue may fail and return NULL. The fix
> checks if it is NULL to avoid NULL pointer dereference.
> Also, the fix moves the call of create_singlethread_workqueue
> earlier to avoid resource-release issues.
>
> Signed-off-by: Kangjie Lu <kjlu@xxxxxxx>

So I don't know this code at all, but...

> drivers/hid/hid-logitech-hidpp.c | 8 ++++++--
> 1 file changed, 6 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/hid/hid-logitech-hidpp.c b/drivers/hid/hid-logitech-hidpp.c
> index 15ed6177a7a3..1b7c336cae6d 100644
> --- a/drivers/hid/hid-logitech-hidpp.c
> +++ b/drivers/hid/hid-logitech-hidpp.c
> @@ -2106,6 +2106,12 @@ static int hidpp_ff_init(struct hidpp_device *hidpp, u8 feature_index)
> data = kzalloc(sizeof(*data), GFP_KERNEL);
> if (!data)
> return -ENOMEM;
> +
> + /* init the hardware command queue */
> + data->wq = create_singlethread_workqueue("hidpp-ff-sendqueue");
> + if (!data->wq)
> + return -ENOMEM;

It's clear just from the diff that this return will leak 'data'. You also
break the error handling just below:

> data->effect_ids = kcalloc(num_slots, sizeof(int), GFP_KERNEL);
> if (!data->effect_ids) {
> kfree(data);

It's also worth asking: how are you testing these error path changes?

Thanks,

jon