linux-kernel - Re: [PATCH][next] platform/chrome: wilco_ec: fix null pointer dereference on failed kzalloc

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Message-ID: <20190618195011.GB209269@google.com>
Date:   Tue, 18 Jun 2019 12:50:11 -0700
From:   Benson Leung <bleung@...gle.com>
To:     Colin King <colin.king@...onical.com>
Cc:     Benson Leung <bleung@...omium.org>,
        Enric Balletbo i Serra <enric.balletbo@...labora.com>,
        Nick Crews <ncrews@...omium.org>,
        kernel-janitors@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH][next] platform/chrome: wilco_ec: fix null pointer
 dereference on failed kzalloc

Hi Colin,

On Tue, Jun 18, 2019 at 04:39:24PM +0100, Colin King wrote:
> From: Colin Ian King <colin.king@...onical.com>
> 
> If the kzalloc of the entries queue q fails a null pointer dereference
> occurs when accessing q->capacity and q->lock.  Add a kzalloc failure
> check and handle the null return case in the calling function
> event_device_add.
> 
> Addresses-Coverity: ("Dereference null return")
> Fixes: 75589e37d1dc ("platform/chrome: wilco_ec: Add circular buffer as event queue")
> Signed-off-by: Colin Ian King <colin.king@...onical.com>

Applied. Thanks.

Benson

> ---
>  drivers/platform/chrome/wilco_ec/event.c | 12 ++++++++++--
>  1 file changed, 10 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/platform/chrome/wilco_ec/event.c b/drivers/platform/chrome/wilco_ec/event.c
> index c975b76e6255..e251a989b152 100644
> --- a/drivers/platform/chrome/wilco_ec/event.c
> +++ b/drivers/platform/chrome/wilco_ec/event.c
> @@ -112,8 +112,11 @@ module_param(queue_size, int, 0644);
>  static struct ec_event_queue *event_queue_new(int capacity)
>  {
>  	size_t entries_size = sizeof(struct ec_event *) * capacity;
> -	struct ec_event_queue *q = kzalloc(sizeof(*q) + entries_size,
> -					   GFP_KERNEL);
> +	struct ec_event_queue *q;
> +
> +	q = kzalloc(sizeof(*q) + entries_size, GFP_KERNEL);
> +	if (!q)
> +		return NULL;
>  
>  	q->capacity = capacity;
>  	spin_lock_init(&q->lock);
> @@ -474,6 +477,11 @@ static int event_device_add(struct acpi_device *adev)
>  	/* Initialize the device data. */
>  	adev->driver_data = dev_data;
>  	dev_data->events = event_queue_new(queue_size);
> +	if (!dev_data->events) {
> +		kfree(dev_data);
> +		error = -ENOMEM;
> +		goto free_minor;
> +	}
>  	init_waitqueue_head(&dev_data->wq);
>  	dev_data->exist = true;
>  	atomic_set(&dev_data->available, 1);
> -- 
> 2.20.1
> 

-- 
Benson Leung
Staff Software Engineer
Chrome OS Kernel
Google Inc.
bleung@...gle.com
Chromium OS Project
bleung@...omium.org

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