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mx.google.com; spf=pass (google.com: domain of miles.chen@mediatek.com designates 210.61.82.183 as permitted sender) smtp.mailfrom=miles.chen@mediatek.com 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) Received-SPF: pass (google.com: domain of miles.chen@mediatek.com designates 210.61.82.183 as permitted sender) client-ip=210.61.82.183; Authentication-Results: mx.google.com; spf=pass (google.com: domain of miles.chen@mediatek.com designates 210.61.82.183 as permitted sender) smtp.mailfrom=miles.chen@mediatek.com X-UUID: 3963096f438c4c29b4b5f2f4c69d258f-20181102 X-UUID: 3963096f438c4c29b4b5f2f4c69d258f-20181102 Received: from mtkcas08.mediatek.inc [(172.21.101.126)] by mailgw01.mediatek.com (envelope-from ) (mhqrelay.mediatek.com ESMTP with TLS) with ESMTP id 1551470932; Fri, 02 Nov 2018 01:00:16 +0800 Received: from mtkcas07.mediatek.inc (172.21.101.84) by mtkmbs08n1.mediatek.inc (172.21.101.55) with Microsoft SMTP Server (TLS) id 15.0.1395.4; Fri, 2 Nov 2018 01:00:09 +0800 Received: from mtksdccf07.mediatek.inc (172.21.84.99) by mtkcas07.mediatek.inc (172.21.101.73) with Microsoft SMTP Server id 15.0.1395.4 via Frontend Transport; Fri, 2 Nov 2018 01:00:08 +0800 From: To: Andrew Morton , Michal Hocko , Joe Perches , Matthew Wilcox CC: , , , , , Miles Chen , Michal Hocko 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> X-Mailer: git-send-email 1.9.1 MIME-Version: 1.0 X-MTK: N X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: X-Virus-Scanned: ClamAV using ClamSMTP 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 Acked-by: 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;