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 A04076B0005 for ; Tue, 2 Aug 2016 06:27:07 -0400 (EDT) Received: by mail-wm0-f71.google.com with SMTP id l4so100331649wml.0 for ; Tue, 02 Aug 2016 03:27:07 -0700 (PDT) Received: from mail-wm0-x234.google.com (mail-wm0-x234.google.com. [2a00:1450:400c:c09::234]) by mx.google.com with ESMTPS id h7si1916208wjo.70.2016.08.02.03.27.06 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 02 Aug 2016 03:27:06 -0700 (PDT) Received: by mail-wm0-x234.google.com with SMTP id i5so282914106wmg.0 for ; Tue, 02 Aug 2016 03:27:06 -0700 (PDT) From: Alexander Potapenko Subject: [PATCH v2] kasan: avoid overflowing quarantine size on low memory systems Date: Tue, 2 Aug 2016 12:27:00 +0200 Message-Id: <1470133620-28683-1-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 --- v2: Don't print the warning if we don't have enough memory for quarantine. --- mm/kasan/quarantine.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/mm/kasan/quarantine.c b/mm/kasan/quarantine.c index 65793f1..8c29938 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 +214,9 @@ 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(); + new_quarantine_size = (new_quarantine_size < percpu_quarantines) ? + 0 : 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