linux-kernel - Re: [PATCH][V2] usb: isp1760: fix null dereference if kzalloc returns null

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Date:	Tue, 02 Jun 2015 20:57:40 +0300
From:	Sergei Shtylyov <sergei.shtylyov@...entembedded.com>
To:	Laurent Pinchart <laurent.pinchart@...asonboard.com>
CC:	Colin King <colin.king@...onical.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Felipe Balbi <balbi@...com>,
	Sudeep Holla <sudeep.holla@....com>, linux-usb@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH][V2] usb: isp1760: fix null dereference if kzalloc returns
 null

Hello.

On 06/02/2015 06:41 PM, Laurent Pinchart wrote:

>>> From: Colin Ian King <colin.king@...onical.com>

>>> If kzalloc returns null then isp1760_ep_alloc_request performs
>>> a null pointer dereference on req. Check for null to avoid this.

>> I told you there's no dereference and yet you're repeating it again. :-(

> How about

> "isp1760_ep_alloc_request allocates a structure with kzalloc without checking
> for NULL and then returns a pointer to one of the structure fields. As the
> field happens to be the first in the structure the caller can properly check
> for NULL, but this is risky if the structure layout is changed later. Add an
> explicit NULL check for the kzalloc return value."

    Fine with me! Thanks, Laurent. :-)

>>> a null pointer dereference on req. Check for null to avoid this.

>>> Detected with smatch static analysis:

>>> drivers/usb/isp1760/isp1760-udc.c:816 isp1760_ep_alloc_request()

>>>     error: potential null dereference 'req'.  (kzalloc returns null)

>>> Signed-off-by: Colin Ian King <colin.king@...onical.com>

WBR, Sergei

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