From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-lf0-f70.google.com (mail-lf0-f70.google.com [209.85.215.70]) by kanga.kvack.org (Postfix) with ESMTP id 9932D6B025E for ; Mon, 1 Aug 2016 10:59:31 -0400 (EDT) Received: by mail-lf0-f70.google.com with SMTP id e7so76982228lfe.0 for ; Mon, 01 Aug 2016 07:59:31 -0700 (PDT) Received: from mail-wm0-x232.google.com (mail-wm0-x232.google.com. [2a00:1450:400c:c09::232]) by mx.google.com with ESMTPS id wg3si31794235wjb.188.2016.08.01.07.59.30 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 01 Aug 2016 07:59:30 -0700 (PDT) Received: by mail-wm0-x232.google.com with SMTP id f65so373708745wmi.0 for ; Mon, 01 Aug 2016 07:59:30 -0700 (PDT) From: Alexander Potapenko Subject: [PATCH] kasan: avoid overflowing quarantine size on low memory systems Date: Mon, 1 Aug 2016 16:59:23 +0200 Message-Id: <1470063563-96266-1-git-send-email-glider@google.com> Sender: owner-linux-mm@kvack.org List-ID: To: 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 Cc: kasan-dev@googlegroups.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org 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 -- 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