From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sasha Levin Subject: [PATCH AUTOSEL 4.4 72/80] mm/page_owner: clamp read count to PAGE_SIZE Date: Mon, 28 Jan 2019 11:23:53 -0500 Message-ID: <20190128162401.58841-72-sashal@kernel.org> References: <20190128162401.58841-1-sashal@kernel.org> Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Return-path: In-Reply-To: <20190128162401.58841-1-sashal@kernel.org> Sender: linux-kernel-owner@vger.kernel.org To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Miles Chen , Joe Perches , Matthew Wilcox , Andrew Morton , Linus Torvalds , Sasha Levin , linux-mm@kvack.org List-Id: linux-mm.kvack.org From: Miles Chen [ Upstream commit c8f61cfc871fadfb73ad3eacd64fda457279e911 ] The (root-only) 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. [akpm@linux-foundation.org: use min_t()] Link: http://lkml.kernel.org/r/1541091607-27402-1-git-send-email-miles.chen@mediatek.com Signed-off-by: Miles Chen Acked-by: Michal Hocko Cc: Joe Perches Cc: Matthew Wilcox Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Sasha Levin --- mm/page_owner.c | 1 + 1 file changed, 1 insertion(+) diff --git a/mm/page_owner.c b/mm/page_owner.c index dd6b9cebf981..9c9f32fa70fa 100644 --- a/mm/page_owner.c +++ b/mm/page_owner.c @@ -107,6 +107,7 @@ print_page_owner(char __user *buf, size_t count, unsigned long pfn, .entries = &page_ext->trace_entries[0], }; + count = min_t(size_t, count, PAGE_SIZE); kbuf = kmalloc(count, GFP_KERNEL); if (!kbuf) return -ENOMEM; -- 2.19.1