From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-lf0-f72.google.com (mail-lf0-f72.google.com [209.85.215.72]) by kanga.kvack.org (Postfix) with ESMTP id 8937C6B0005 for ; Mon, 4 Jul 2016 05:48:22 -0400 (EDT) Received: by mail-lf0-f72.google.com with SMTP id g18so118809768lfg.2 for ; Mon, 04 Jul 2016 02:48:22 -0700 (PDT) Received: from EUR01-VE1-obe.outbound.protection.outlook.com (mail-ve1eur01on0122.outbound.protection.outlook.com. [104.47.1.122]) by mx.google.com with ESMTPS id s188si2635083wme.29.2016.07.04.02.48.20 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Mon, 04 Jul 2016 02:48:20 -0700 (PDT) Subject: Re: [PATCH v4] kasan/quarantine: fix bugs on qlist_move_cache() References: <1467606714-30231-1-git-send-email-iamjoonsoo.kim@lge.com> From: Andrey Ryabinin Message-ID: <577A3114.9080008@virtuozzo.com> Date: Mon, 4 Jul 2016 12:49:08 +0300 MIME-Version: 1.0 In-Reply-To: <1467606714-30231-1-git-send-email-iamjoonsoo.kim@lge.com> Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: js1304@gmail.com, Andrew Morton Cc: Alexander Potapenko , Dmitry Vyukov , kasan-dev@googlegroups.com, Kuthonuzo Luruo , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Joonsoo Kim On 07/04/2016 07:31 AM, js1304@gmail.com wrote: > From: Joonsoo Kim > > There are two bugs on qlist_move_cache(). One is that qlist's tail > isn't set properly. curr->next can be NULL since it is singly linked > list and NULL value on tail is invalid if there is one item on qlist. > Another one is that if cache is matched, qlist_put() is called and > it will set curr->next to NULL. It would cause to stop the loop > prematurely. > > These problems come from complicated implementation so I'd like to > re-implement it completely. Implementation in this patch is really > simple. Iterate all qlist_nodes and put them to appropriate list. > > Unfortunately, I got this bug sometime ago and lose oops message. > But, the bug looks trivial and no need to attach oops. > > v4: fix cache size bug s/cache->size/obj_cache->size/ > v3: fix build warning > > Signed-off-by: Joonsoo Kim > --- > mm/kasan/quarantine.c | 21 +++++++-------------- > 1 file changed, 7 insertions(+), 14 deletions(-) > > diff --git a/mm/kasan/quarantine.c b/mm/kasan/quarantine.c > index 4973505..b2e1827 100644 > --- a/mm/kasan/quarantine.c > +++ b/mm/kasan/quarantine.c > @@ -238,30 +238,23 @@ static void qlist_move_cache(struct qlist_head *from, > struct qlist_head *to, > struct kmem_cache *cache) > { > - struct qlist_node *prev = NULL, *curr; > + struct qlist_node *curr; > > if (unlikely(qlist_empty(from))) > return; > > curr = from->head; > + qlist_init(from); > while (curr) { > struct qlist_node *qlink = curr; > struct kmem_cache *obj_cache = qlink_to_cache(qlink); > > - if (obj_cache == cache) { > - if (unlikely(from->head == qlink)) { > - from->head = curr->next; > - prev = curr; > - } else > - prev->next = curr->next; > - if (unlikely(from->tail == qlink)) > - from->tail = curr->next; > - from->bytes -= cache->size; > - qlist_put(to, qlink, cache->size); > - } else { > - prev = curr; > - } > curr = curr->next; Nit: Wouldn't be more appropriate to swap 'curr' and 'qlink' variable names? Because now qlink is acts as a "current" pointer. > + > + if (obj_cache == cache) > + qlist_put(to, qlink, obj_cache->size); > + else > + qlist_put(from, qlink, obj_cache->size); > } > } > > -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org