From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pl1-f199.google.com (mail-pl1-f199.google.com [209.85.214.199]) by kanga.kvack.org (Postfix) with ESMTP id 217176B0008 for ; Thu, 1 Nov 2018 13:00:22 -0400 (EDT) Received: by mail-pl1-f199.google.com with SMTP id c15-v6so5093720pls.15 for ; Thu, 01 Nov 2018 10:00:22 -0700 (PDT) Received: from mailgw01.mediatek.com ([210.61.82.183]) by mx.google.com with ESMTPS id v6-v6si29516489plo.134.2018.11.01.10.00.20 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 01 Nov 2018 10:00:21 -0700 (PDT) From: Subject: [PATCH v4] mm/page_owner: clamp read count to PAGE_SIZE Date: Fri, 2 Nov 2018 01:00:07 +0800 Message-ID: <1541091607-27402-1-git-send-email-miles.chen@mediatek.com> MIME-Version: 1.0 Content-Type: text/plain Sender: owner-linux-mm@kvack.org List-ID: To: Andrew Morton , Michal Hocko , Joe Perches , Matthew Wilcox Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-mediatek@lists.infradead.org, wsd_upstream@mediatek.com, Miles Chen , Michal Hocko From: Miles Chen The page owner read might allocate a large size of memory with a large read count. Allocation fails can easily occur when doing high order allocations. Clamp buffer size to PAGE_SIZE to avoid arbitrary size allocation and avoid allocation fails due to high order allocation. Change since v3: - remove the change in kvmalloc - keep kmalloc in page_owner.c Change since v2: - improve kvmalloc, allow sub page allocations fallback to vmalloc when CONFIG_HIGHMEM=y Change since v1: - use kvmalloc() - clamp buffer size to PAGE_SIZE Signed-off-by: Miles Chen Cc: Joe Perches Cc: Matthew Wilcox Cc: Michal Hocko --- mm/page_owner.c | 1 + 1 file changed, 1 insertion(+) diff --git a/mm/page_owner.c b/mm/page_owner.c index 87bc0dfdb52b..b83f295e4eca 100644 --- a/mm/page_owner.c +++ b/mm/page_owner.c @@ -351,6 +351,7 @@ print_page_owner(char __user *buf, size_t count, unsigned long pfn, .skip = 0 }; + count = count > PAGE_SIZE ? PAGE_SIZE : count; kbuf = kmalloc(count, GFP_KERNEL); if (!kbuf) return -ENOMEM; -- 2.18.0