From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753804AbcI1JRj (ORCPT ); Wed, 28 Sep 2016 05:17:39 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:57819 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753898AbcI1JME (ORCPT ); Wed, 28 Sep 2016 05:12:04 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Alexander Potapenko , Dmitry Vyukov , Andrey Ryabinin , Andrew Morton , Linus Torvalds Subject: [PATCH 4.7 66/69] kasan: avoid overflowing quarantine size on low memory systems Date: Wed, 28 Sep 2016 11:05:48 +0200 Message-Id: <20160928090447.842337527@linuxfoundation.org> X-Mailer: git-send-email 2.10.0 In-Reply-To: <20160928090445.054716307@linuxfoundation.org> References: <20160928090445.054716307@linuxfoundation.org> User-Agent: quilt/0.64 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 4.7-stable review patch. If anyone has any objections, please let me know. ------------------ From: Alexander Potapenko commit c3cee372282cb6bcdf19ac1457581d5dd5ecb554 upstream. 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. [akpm@linux-foundation.org: cleanup: use WARN_ONCE return value] Link: http://lkml.kernel.org/r/1470063563-96266-1-git-send-email-glider@google.com Fixes: 55834c59098d ("mm: kasan: initial memory quarantine implementation") Signed-off-by: Alexander Potapenko Reported-by: Dmitry Vyukov Cc: Andrey Ryabinin Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- mm/kasan/quarantine.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) --- a/mm/kasan/quarantine.c +++ b/mm/kasan/quarantine.c @@ -196,7 +196,7 @@ void quarantine_put(struct kasan_free_me 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 +214,12 @@ 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 (WARN_ONCE(new_quarantine_size < percpu_quarantines, + "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;