From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753038AbcHaEQE (ORCPT ); Wed, 31 Aug 2016 00:16:04 -0400 Received: from mail-yb0-f187.google.com ([209.85.213.187]:34685 "EHLO mail-yb0-f187.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751080AbcHaEQD (ORCPT ); Wed, 31 Aug 2016 00:16:03 -0400 X-Greylist: delayed 3703 seconds by postgrey-1.27 at vger.kernel.org; Wed, 31 Aug 2016 00:16:03 EDT X-Google-Already-Archived: Yes X-Google-Already-Archived-Group-Id: 538b02b333 X-Google-Doc-Id: 2cd2c33ee7f9a X-Google-Thread-Id: 35ec86b034c6ac9b X-Google-Message-Url: http://groups.google.com/group/kasan-dev/msg/2cd2c33ee7f9a X-Google-Thread-Url: http://groups.google.com/group/kasan-dev/t/35ec86b034c6ac9b X-Google-Web-Client: true Date: Tue, 30 Aug 2016 19:39:14 -0700 (PDT) From: amanda4ray@gmail.com To: kasan-dev Cc: dvyukov@google.com, kcc@google.com, aryabinin@virtuozzo.com, adech.fo@gmail.com, cl@linux.com, akpm@linux-foundation.org, rostedt@goodmis.org, js1304@gmail.com, iamjoonsoo.kim@lge.com, kuthonuzo.luruo@hpe.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org Message-Id: In-Reply-To: <1470063563-96266-1-git-send-email-glider@google.com> References: <1470063563-96266-1-git-send-email-glider@google.com> Subject: Re: [PATCH] kasan: avoid overflowing quarantine size on low memory systems MIME-Version: 1.0 Content-Type: multipart/mixed; boundary="----=_Part_3204_1895713932.1472611154832" X-Google-Token: ENKGmb4FIMSL-Up_oQI0 X-Google-IP: 2607:fb90:25c7:36cc:6016:408f:ba72:4db1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org ------=_Part_3204_1895713932.1472611154832 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On Monday, August 1, 2016 at 10:59:29 AM UTC-4, Alexander Potapenko wrote: > If the total amount of memory assigned to quarantine is less than the > amount of memory assigned to per-cpu quarantines, |new_quarantine_size| > may overflow. Instead, set it to zero. > > Reported-by: Dmitry Vyukov > Fixes: 55834c59098d ("mm: kasan: initial memory quarantine > implementation") > Signed-off-by: Alexander Potapenko > --- > mm/kasan/quarantine.c | 12 ++++++++++-- > 1 file changed, 10 insertions(+), 2 deletions(-) > > diff --git a/mm/kasan/quarantine.c b/mm/kasan/quarantine.c > index 65793f1..416d3b0 100644 > --- a/mm/kasan/quarantine.c > +++ b/mm/kasan/quarantine.c > @@ -196,7 +196,7 @@ void quarantine_put(struct kasan_free_meta *info, struct kmem_cache *cache) > > void quarantine_reduce(void) > { > - size_t new_quarantine_size; > + size_t new_quarantine_size, percpu_quarantines; > unsigned long flags; > struct qlist_head to_free = QLIST_INIT; > size_t size_to_free = 0; > @@ -214,7 +214,15 @@ void quarantine_reduce(void) > */ > new_quarantine_size = (READ_ONCE(totalram_pages) << PAGE_SHIFT) / > QUARANTINE_FRACTION; > - new_quarantine_size -= QUARANTINE_PERCPU_SIZE * num_online_cpus(); > + percpu_quarantines = QUARANTINE_PERCPU_SIZE * num_online_cpus(); > + if (new_quarantine_size < percpu_quarantines) { > + WARN_ONCE(1, > + "Too little memory, disabling global KASAN quarantine.\n", > + ); > + new_quarantine_size = 0; > + } else { > + new_quarantine_size -= percpu_quarantines; > + } > WRITE_ONCE(quarantine_size, new_quarantine_size); > > last = global_quarantine.head; > -- > 2.8.0.rc3.226.g39d4020 On Monday, August 1, 2016 at 10:59:29 AM UTC-4, Alexander Potapenko wrote: > If the total amount of memory assigned to quarantine is less than the > amount of memory assigned to per-cpu quarantines, |new_quarantine_size| > may overflow. Instead, set it to zero. > > Reported-by: Dmitry Vyukov > Fixes: 55834c59098d ("mm: kasan: initial memory quarantine > implementation") > Signed-off-by: Alexander Potapenko > --- > mm/kasan/quarantine.c | 12 ++++++++++-- > 1 file changed, 10 insertions(+), 2 deletions(-) > > diff --git a/mm/kasan/quarantine.c b/mm/kasan/quarantine.c > index 65793f1..416d3b0 100644 > --- a/mm/kasan/quarantine.c > +++ b/mm/kasan/quarantine.c > @@ -196,7 +196,7 @@ void quarantine_put(struct kasan_free_meta *info, struct kmem_cache *cache) > > void quarantine_reduce(void) > { > - size_t new_quarantine_size; > + size_t new_quarantine_size, percpu_quarantines; > unsigned long flags; > struct qlist_head to_free = QLIST_INIT; > size_t size_to_free = 0; > @@ -214,7 +214,15 @@ void quarantine_reduce(void) > */ > new_quarantine_size = (READ_ONCE(totalram_pages) << PAGE_SHIFT) / > QUARANTINE_FRACTION; > - new_quarantine_size -= QUARANTINE_PERCPU_SIZE * num_online_cpus(); > + percpu_quarantines = QUARANTINE_PERCPU_SIZE * num_online_cpus(); > + if (new_quarantine_size < percpu_quarantines) { > + WARN_ONCE(1, > + "Too little memory, disabling global KASAN quarantine.\n", > + ); > + new_quarantine_size = 0; > + } else { > + new_quarantine_size -= percpu_quarantines; > + } > WRITE_ONCE(quarantine_size, new_quarantine_size); > > last = global_quarantine.head; > -- > 2.8.0.rc3.226.g39d4020 ------=_Part_3204_1895713932.1472611154832--