From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mga03.intel.com (mga03.intel.com [134.134.136.65]) by dpdk.org (Postfix) with ESMTP id 1B24D3B5 for ; Mon, 2 Mar 2015 18:35:39 +0100 (CET) Received: from orsmga001.jf.intel.com ([10.7.209.18]) by orsmga103.jf.intel.com with ESMTP; 02 Mar 2015 09:33:16 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.09,676,1418112000"; d="scan'208";a="659304811" Received: from unknown (HELO [10.217.248.122]) ([10.217.248.122]) by orsmga001.jf.intel.com with ESMTP; 02 Mar 2015 09:35:36 -0800 Message-ID: <54F49F53.1010307@intel.com> Date: Mon, 02 Mar 2015 18:35:15 +0100 From: Pawel Wodkowski User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:31.0) Gecko/20100101 Thunderbird/31.5.0 MIME-Version: 1.0 To: "Wiles, Keith" , David Marchand References: <1425294562-26015-1-git-send-email-pawelx.wodkowski@intel.com> <54F479EF.4010706@intel.com> In-Reply-To: Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Cc: "dev@dpdk.org" Subject: Re: [dpdk-dev] [PATCH] eal: prevent dereferencing NULL pointer in rte_eal_devargs_add() X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: patches and discussions about DPDK List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 02 Mar 2015 17:35:40 -0000 On 2015-03-02 17:47, Wiles, Keith wrote: > > > On 3/2/15, 8:55 AM, "Wodkowski, PawelX" wrote: > >> On 2015-03-02 15:40, Wiles, Keith wrote: >>> >>> >>> On 3/2/15, 6:23 AM, "David Marchand" wrote: >>> >>>> Hello Pawel, >>>> >>>> On Mon, Mar 2, 2015 at 12:09 PM, Pawel Wodkowski >>>> >>>> wrote: >>>> >>>>> On failure devargs->args should not be accesed if devargs is NULL. >>>>> >>>> >>>> accessed. >>>> >>>> >>>>> >>>>> Signed-off-by: Pawel Wodkowski >>>>> --- >>>>> lib/librte_eal/common/eal_common_devargs.c | 7 ++++--- >>>>> 1 file changed, 4 insertions(+), 3 deletions(-) >>>>> >>>>> diff --git a/lib/librte_eal/common/eal_common_devargs.c >>>>> b/lib/librte_eal/common/eal_common_devargs.c >>>>> index 9b110f7..615945e 100644 >>>>> --- a/lib/librte_eal/common/eal_common_devargs.c >>>>> +++ b/lib/librte_eal/common/eal_common_devargs.c >>>>> @@ -124,12 +124,13 @@ rte_eal_devargs_add(enum rte_devtype devtype, >>>>> const >>>>> char *devargs_str) >>>>> return 0; >>>>> >>>>> fail: >>>>> - if (devargs->args) >>>>> - free(devargs->args); >>>>> if (buf) >>>>> free(buf); >>>>> - if (devargs) >>>>> + if (devargs) { >>>>> + free(devargs->args); >>> >>> Do you not still need to check for args being NULL before calling free? >> >> No, there is no need for that. The same for buf. This NOP check is >> common practice in DPDK. I woul be good to clean this in whole library >> in separate patch set. >> >> I recommend to read free() doc before doing another 'if (foo != NULL) >> free(foo)' >> >> http://pubs.opengroup.org/onlinepubs/009695399/functions/free.html > > OK, did not realize this was changed. Do we know if all of the OSes DPDK > is built supports this free style? > > I know that VxWorks did not support this free() method and I did port DPDK > to that OS, but it is not a supported platform for DPDK. > > If some OS does not support passing NULL (and is supported by DPDK) to > free, then we need to abstract the free into a macro to allow those > systems to work correctly. I would expect using a macro for free would > also help if all frees were reworked to not test for NULL. > This is standard C behaviour (since ANSI C?) and VxWorks claim to be compatible with it. If they lie, why bother? > ++Keith >> >> -- >> Pawel > -- Pawel