From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-15.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 80EADC433E0 for ; Thu, 28 Jan 2021 12:03:58 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id E331E64DDB for ; Thu, 28 Jan 2021 12:03:57 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E331E64DDB Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=suse.cz Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id E83D56B0072; Thu, 28 Jan 2021 07:03:56 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id E34A26B0074; Thu, 28 Jan 2021 07:03:56 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id D4A2C6B0075; Thu, 28 Jan 2021 07:03:56 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0132.hostedemail.com [216.40.44.132]) by kanga.kvack.org (Postfix) with ESMTP id BE3E56B0072 for ; Thu, 28 Jan 2021 07:03:56 -0500 (EST) Received: from smtpin01.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id 7EEC6181AEF30 for ; Thu, 28 Jan 2021 12:03:56 +0000 (UTC) X-FDA: 77755050072.01.coast15_40148442759f Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin01.hostedemail.com (Postfix) with ESMTP id 57C891004D42D for ; Thu, 28 Jan 2021 12:03:56 +0000 (UTC) X-HE-Tag: coast15_40148442759f X-Filterd-Recvd-Size: 3199 Received: from mx2.suse.de (mx2.suse.de [195.135.220.15]) by imf10.hostedemail.com (Postfix) with ESMTP for ; Thu, 28 Jan 2021 12:03:55 +0000 (UTC) X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 6DA1AAC45; Thu, 28 Jan 2021 12:03:54 +0000 (UTC) Subject: Re: [PATCH] Revert "mm/slub: fix a memory leak in sysfs_slab_add()" To: Wang Hai , torvalds@linux-foundation.org, cl@linux.com, penberg@kernel.org, rientjes@google.com, iamjoonsoo.kim@lge.com, akpm@linux-foundation.org Cc: asmadeus@codewreck.org, davem@davemloft.net, ericvh@gmail.com, kuba@kernel.org, lucho@ionkov.net, netdev@vger.kernel.org, syzkaller-bugs@googlegroups.com, v9fs-developer@lists.sourceforge.net, linux-mm@kvack.org, linux-kernel@vger.kernel.org, syzbot+d0bd96b4696c1ef67991@syzkaller.appspotmail.com References: <20210128113250.60078-1-wanghai38@huawei.com> From: Vlastimil Babka Message-ID: <1f4afc98-f5de-3992-1f49-f041d3783ea2@suse.cz> Date: Thu, 28 Jan 2021 13:03:53 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.6.1 MIME-Version: 1.0 In-Reply-To: <20210128113250.60078-1-wanghai38@huawei.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 1/28/21 12:32 PM, Wang Hai wrote: > This reverts commit dde3c6b72a16c2db826f54b2d49bdea26c3534a2. > > syzbot report a double-free bug. The following case can cause this bug. > - mm/slab_common.c: create_cache(): if the __kmem_cache_create() > fails, it does: > > out_free_cache: > kmem_cache_free(kmem_cache, s); > > - but __kmem_cache_create() - at least for slub() - will have done > > sysfs_slab_add(s) > -> sysfs_create_group() .. fails .. > -> kobject_del(&s->kobj); .. which frees s ... > > We can't remove the kmem_cache_free() in create_cache(), because > other error cases of __kmem_cache_create() do not free this. > > So, revert the commit dde3c6b72a16 ("mm/slub: fix a memory leak in > sysfs_slab_add()") to fix this. > > Reported-by: syzbot+d0bd96b4696c1ef67991@syzkaller.appspotmail.com > Fixes: dde3c6b72a16 ("mm/slub: fix a memory leak in sysfs_slab_add()") > Signed-off-by: Wang Hai Cc: Acked-by: Vlastimil Babka Double-free is worse than a rare small memory leak. Which would still be nice to fix, but I'm afraid it will be more complicated, so start with preventing the worse issue, including stable. > --- > mm/slub.c | 4 +--- > 1 file changed, 1 insertion(+), 3 deletions(-) > > diff --git a/mm/slub.c b/mm/slub.c > index 69742ab9a21d..7ecbbbe5bc0c 100644 > --- a/mm/slub.c > +++ b/mm/slub.c > @@ -5625,10 +5625,8 @@ static int sysfs_slab_add(struct kmem_cache *s) > > s->kobj.kset = kset; > err = kobject_init_and_add(&s->kobj, &slab_ktype, NULL, "%s", name); > - if (err) { > - kobject_put(&s->kobj); > + if (err) > goto out; > - } > > err = sysfs_create_group(&s->kobj, &slab_attr_group); > if (err) >