From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6F84EC43381 for ; Thu, 21 Feb 2019 15:30:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 453C82075A for ; Thu, 21 Feb 2019 15:30:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727278AbfBUPaV (ORCPT ); Thu, 21 Feb 2019 10:30:21 -0500 Received: from relay.sw.ru ([185.231.240.75]:33148 "EHLO relay.sw.ru" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725832AbfBUPaU (ORCPT ); Thu, 21 Feb 2019 10:30:20 -0500 Received: from [172.16.24.21] by relay.sw.ru with esmtp (Exim 4.91) (envelope-from ) id 1gwqIk-0000tc-BD; Thu, 21 Feb 2019 18:30:18 +0300 From: Vasily Averin Subject: [PATCH] tcp: detect use sendpage for slab-based objects To: Eric Dumazet , netdev@vger.kernel.org Message-ID: Date: Thu, 21 Feb 2019 18:30:17 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.4.0 MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org There was few incidents when XFS over network block device generates IO requests with slab-based metadata. If these requests are processed via sendpage path tcp_sendpage() calls skb_can_coalesce() and merges neighbour slab objects into one skb fragment. If receiving side is located on the same host tcp_recvmsg() can trigger following BUG_ON usercopy: kernel memory exposure attempt detected from XXXXXX (kmalloc-512) (1024 bytes) This patch helps to detect the reason of similar incidents on sending side. Signed-off-by: Vasily Averin --- net/ipv4/tcp.c | 1 + 1 file changed, 1 insertion(+) diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c index 2079145a3b7c..cf9572f4fc0f 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -996,6 +996,7 @@ ssize_t do_tcp_sendpages(struct sock *sk, struct page *page, int offset, goto wait_for_memory; if (can_coalesce) { + WARN_ON_ONCE(PageSlab(page)); skb_frag_size_add(&skb_shinfo(skb)->frags[i - 1], copy); } else { get_page(page); -- 2.17.1