From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751807AbeDDIyR (ORCPT ); Wed, 4 Apr 2018 04:54:17 -0400 Received: from szxga06-in.huawei.com ([45.249.212.32]:43991 "EHLO huawei.com" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1751735AbeDDIyP (ORCPT ); Wed, 4 Apr 2018 04:54:15 -0400 Subject: Re: [PATCH] lib: logic_pio: Fix potential NULL pointer dereference To: "Gustavo A. R. Silva" , Bjorn Helgaas , Andy Shevchenko References: <20180403211505.GA29612@embeddedor.com> CC: , "Gustavo A. R. Silva" From: John Garry Message-ID: Date: Wed, 4 Apr 2018 09:54:04 +0100 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:45.0) Gecko/20100101 Thunderbird/45.3.0 MIME-Version: 1.0 In-Reply-To: <20180403211505.GA29612@embeddedor.com> Content-Type: text/plain; charset="windows-1252"; format=flowed Content-Transfer-Encoding: 7bit X-Originating-IP: [10.202.227.238] X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 03/04/2018 22:15, Gustavo A. R. Silva wrote: > new_range is being dereferenced before it is null checked, hence > there is a potential null pointer dereference. > > Fix this by moving the pointer dereference after new_range has > been properly null checked. > Hi Gustavo, In fact we expect new_range to never be NULL. But, if we're going to check, then better make sure the check is correct... Thanks, John > Addresses-Coverity-ID: 1466163 ("Dereference before null check") > Fixes: 0a7198426259 ("lib: Add generic PIO mapping method") > Signed-off-by: Gustavo A. R. Silva Reviewed-by: John Garry > --- > lib/logic_pio.c | 7 +++++-- > 1 file changed, 5 insertions(+), 2 deletions(-) > > diff --git a/lib/logic_pio.c b/lib/logic_pio.c > index 29cedea..30dfdce 100644 > --- a/lib/logic_pio.c > +++ b/lib/logic_pio.c > @@ -33,8 +33,8 @@ static DEFINE_MUTEX(io_range_mutex); > int logic_pio_register_range(struct logic_pio_hwaddr *new_range) > { > struct logic_pio_hwaddr *range; > - resource_size_t start = new_range->hw_start; > - resource_size_t end = new_range->hw_start + new_range->size; > + resource_size_t start; > + resource_size_t end; > resource_size_t mmio_sz = 0; > resource_size_t iio_sz = MMIO_UPPER_LIMIT; > int ret = 0; > @@ -42,6 +42,9 @@ int logic_pio_register_range(struct logic_pio_hwaddr *new_range) > if (!new_range || !new_range->fwnode || !new_range->size) > return -EINVAL; > > + start = new_range->hw_start; > + end = new_range->hw_start + new_range->size; > + > mutex_lock(&io_range_mutex); > list_for_each_entry_rcu(range, &io_range_list, list) { > if (range->fwnode == new_range->fwnode) { >