From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Wiles, Keith" Subject: Re: [PATCH] eal: prevent dereferencing NULL pointer in rte_eal_devargs_add() Date: Mon, 2 Mar 2015 16:47:23 +0000 Message-ID: References: <1425294562-26015-1-git-send-email-pawelx.wodkowski@intel.com> <54F479EF.4010706@intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable Cc: "dev-VfR2kkLFssw@public.gmane.org" To: "Wodkowski, PawelX" , David Marchand Return-path: In-Reply-To: <54F479EF.4010706-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org> Content-Language: en-US Content-ID: List-Id: patches and discussions about DPDK List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces-VfR2kkLFssw@public.gmane.org Sender: "dev" 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 !=3D 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. ++Keith > >--=20 >Pawel