From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm0-f71.google.com (mail-wm0-f71.google.com [74.125.82.71]) by kanga.kvack.org (Postfix) with ESMTP id B62496B0005 for ; Fri, 1 Jul 2016 10:04:07 -0400 (EDT) Received: by mail-wm0-f71.google.com with SMTP id r190so19330321wmr.0 for ; Fri, 01 Jul 2016 07:04:07 -0700 (PDT) Received: from mail-lf0-x22b.google.com (mail-lf0-x22b.google.com. [2a00:1450:4010:c07::22b]) by mx.google.com with ESMTPS id e81si2329638lfi.136.2016.07.01.07.04.06 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 01 Jul 2016 07:04:06 -0700 (PDT) Received: by mail-lf0-x22b.google.com with SMTP id h129so78006203lfh.1 for ; Fri, 01 Jul 2016 07:04:06 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: <1467381733-18314-1-git-send-email-iamjoonsoo.kim@lge.com> References: <1467381733-18314-1-git-send-email-iamjoonsoo.kim@lge.com> From: Dmitry Vyukov Date: Fri, 1 Jul 2016 16:03:46 +0200 Message-ID: Subject: Re: [PATCH v3] kasan/quarantine: fix bugs on qlist_move_cache() Content-Type: text/plain; charset=UTF-8 Sender: owner-linux-mm@kvack.org List-ID: To: Joonsoo Kim Cc: Andrew Morton , Andrey Ryabinin , Alexander Potapenko , kasan-dev , "linux-mm@kvack.org" , LKML , Joonsoo Kim On Fri, Jul 1, 2016 at 4:02 PM, 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. > > 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..cf92494 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; > + > + if (obj_cache == cache) > + qlist_put(to, qlink, cache->size); > + else > + qlist_put(from, qlink, cache->size); This line is wrong. If obj_cache != cache, object size != cache->size. Quarantine contains objects of different sizes. > } > } > > -- > 1.9.1 > -- 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