From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753026AbdK3PCH (ORCPT ); Thu, 30 Nov 2017 10:02:07 -0500 Received: from mail-pl0-f65.google.com ([209.85.160.65]:37858 "EHLO mail-pl0-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752470AbdK3PCF (ORCPT ); Thu, 30 Nov 2017 10:02:05 -0500 X-Google-Smtp-Source: AGs4zMbtHiRFxviQIcR60dSg65ECtjeARYZOohCm26Jiyu2sOiXf1YVt8jOlr0IQFgQSHWJHJbbqUg== Subject: Re: [PATCH] of: overlay: fix memory leak of ovcs on error exit path From: Frank Rowand To: Colin Ian King , Pantelis Antoniou , Rob Herring , devicetree@vger.kernel.org Cc: kernel-janitors@vger.kernel.org, linux-kernel@vger.kernel.org References: <20171129191750.25254-1-colin.king@canonical.com> <806a0467-87c8-4100-c7f2-54cfa8732465@canonical.com> <75d7d1c8-8a19-1a4c-0796-7cf69fdebe6d@gmail.com> Message-ID: <788fe2e4-03b2-6f9d-f5dd-5bdf0c48892f@gmail.com> Date: Thu, 30 Nov 2017 10:01:50 -0500 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.4.0 MIME-Version: 1.0 In-Reply-To: <75d7d1c8-8a19-1a4c-0796-7cf69fdebe6d@gmail.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 11/30/17 08:37, Frank Rowand wrote: > Hi Colin, Rob, > > On 11/30/17 07:18, Colin Ian King wrote: >> On 30/11/17 12:14, Frank Rowand wrote: >>> On 11/29/17 14:17, Colin King wrote: >>>> From: Colin Ian King >>>> >>>> Currently if the call to of_resolve_phandles fails then then ovcs >>>> is not kfree'd on the error exit path. Rather than try and make >>>> the clean up exit path more convoluted, fix this by just kfree'ing >>>> ovcs at the point of error detection and exit via the same exit >>>> path. >>>> >>>> Detected by CoverityScan, CID#1462296 ("Resource Leak") >>>> >>>> Fixes: f948d6d8b792 ("of: overlay: avoid race condition between applying multiple overlays") >>>> Signed-off-by: Colin Ian King >>>> --- >>>> drivers/of/overlay.c | 4 +++- >>>> 1 file changed, 3 insertions(+), 1 deletion(-) >>>> >>>> diff --git a/drivers/of/overlay.c b/drivers/of/overlay.c >>>> index 53bc9e3f0b98..6c8efe7d8cbb 100644 >>>> --- a/drivers/of/overlay.c >>>> +++ b/drivers/of/overlay.c >>>> @@ -708,8 +708,10 @@ int of_overlay_apply(struct device_node *tree, int *ovcs_id) >>>> of_overlay_mutex_lock(); >>>> >>>> ret = of_resolve_phandles(tree); >>>> - if (ret) >>>> + if (ret) { >>>> + kfree(ovcs); >>>> goto err_overlay_unlock; >>>> + } >>>> >>>> mutex_lock(&of_mutex); >>>> >>>> >>> >>> False coverity warning. ovcs is freed in free_overlay_changeset(). >>> >> >> The error exit path is via err_overlay_unlock: >> >> err_overlay_unlock: >> of_overlay_mutex_unlock(); >> >> out: >> pr_debug("%s() err=%d\n", __func__, ret); >> >> return ret; >> >> ..so there is no call to free_overlay_changeset there. >> >> Colin >> > > OK, I was looking at 4.15-rc1. You must be looking at a later version where > "[PATCH 1/2] of: overlay: Fix cleanup order in of_overlay_apply()" has been > applied. Thanks for providing the extra details about the exit path so I > could see that. > > Rob, I think that the fix for cleanup order was not the best way to fix that > problem. A better method would have been to move "mutex_lock(&of_mutex);" > up 5 lines, to just before calling of_reserve_phandles(). It is getting late (midnight my time), so I really should revisit this all tomorrow. My last comment ("move ... up 5 lines") is probably wrong. I'll look at this after some sleep. > The problem > found by coverity was caused by the "Fix cleanup order" patch. > > I can create that alternate fix if you would like, but I am traveling > right now and don't want to submit a patch without boot testing, so > there will be a slight delay. > > -Frank