From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Burakov, Anatoly" Subject: Re: [PATCH] eal: fix strdup usages in internal config Date: Thu, 31 Jan 2019 15:55:06 +0000 Message-ID: References: <4e041e83fb00d8d818682997f795928c36b3283a.1547127516.git.anatoly.burakov@intel.com> <1614490.ZEn2XMpOzn@xps> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Cc: dev@dpdk.org, Bruce Richardson , ferruh.yigit@intel.com, andy01011501@163.com, Yongseok Koh , "stable@dpdk.org" To: Thomas Monjalon , Kevin Traynor Return-path: In-Reply-To: <1614490.ZEn2XMpOzn@xps> Content-Language: en-US List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org Sender: "dev" On 31-Jan-19 3:04 PM, Thomas Monjalon wrote: > 31/01/2019 15:15, Kevin Traynor: >> On 01/31/2019 02:10 PM, Burakov, Anatoly wrote: >>> On 31-Jan-19 11:21 AM, Kevin Traynor wrote: >>>> On 01/10/2019 01:38 PM, Anatoly Burakov wrote: >>>>> Currently, we use strdup in a few places to store command-line >>>>> parameter values for certain internal config values. There are >>>>> several issues with that. >>>>> >>>>> First of all, they're never freed, so memory ends up leaking >>>>> either after EAL exit, or when these command-line options are >>>>> supplied multiple times. >>>>> >>>>> Second of all, they're defined as `const char *`, so they >>>>> *cannot* be freed even if we wanted to. >>>>> >>>>> Finally, strdup may return NULL, which will be stored in the >>>>> config. For most fields, NULL is a valid value, but for the >>>>> default prefix, the value is always expected to be valid. >>>>> >>>>> To fix all of this, three things are done. First, we change >>>>> the definitions of these values to `char *` as opposed to >>>>> `const char *`. This does not break the ABI, and previous >>>>> code assumes constness (which is more restrictive), so it's >>>>> safe to do so. >>>>> >>>>> Then, fix all usages of strdup to check return value, and add >>>>> a cleanup function that will free the memory occupied by >>>>> these strings, as well as freeing them before assigning a new >>>>> value to prevent leaks when parameter is specified multiple >>>>> times. >>>>> >>>>> And finally, add an internal API to query hugefile prefix, so >>>>> that, absent of a valid value, a default value will be >>>>> returned, and also fix up all usages of hugefile prefix to >>>>> use this API instead of accessing hugefile prefix directly. >>>>> >>>>> Bugzilla ID: 108 >>>>> >>>> >>>> Hi Anatoly - this doesn't have stable or Fixes tags, but the bugzilla >>>> was reported on 17.11. Is it for backport to stable branches? >>>> >>> >>> It can be. Whether it's worth the effort of backporting is not my call :) >>> >> >> It's fine for 18.11 branch anyway, just needed a little help due to some >> changed context. I will send diff to stable list as normal. > > Nothing was broken. I see it like an improvement. > Not sure it is worth the effort. > Well, *technically*, there was a memory leak. For example, if you specify mbuf pool ops flag multiple times, previously allocated strdup() call results would be discarded and leaked. However, it's such a minor issue that it's indeed likely not worth the effort. -- Thanks, Anatoly