From patchwork Sat Aug 15 12:42:52 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Coly Li X-Patchwork-Id: 11715845 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 7D4A4161F for ; Sat, 15 Aug 2020 22:14:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6DFCF2067C for ; Sat, 15 Aug 2020 22:14:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729250AbgHOWNo (ORCPT ); Sat, 15 Aug 2020 18:13:44 -0400 Received: from mx2.suse.de ([195.135.220.15]:36294 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728486AbgHOWNo (ORCPT ); Sat, 15 Aug 2020 18:13:44 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 40F9AAD4B; Sat, 15 Aug 2020 12:43:26 +0000 (UTC) From: colyli@suse.de To: linux-block@vger.kernel.org, linux-nvme@lists.infradead.org Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org, Coly Li , Chaitanya Kulkarni , Christoph Hellwig , Hannes Reinecke , Jan Kara , Jens Axboe , Mikhail Skorzhinskii , Philipp Reisner , Sagi Grimberg , Vlastimil Babka Subject: [PATCH v4 1/3] net: introduce helper sendpage_ok() in include/linux/net.h Date: Sat, 15 Aug 2020 20:42:52 +0800 Message-Id: <20200815124254.115076-1-colyli@suse.de> X-Mailer: git-send-email 2.26.2 MIME-Version: 1.0 Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org From: Coly Li The original problem was from nvme-over-tcp code, who mistakenly uses kernel_sendpage() to send pages allocated by __get_free_pages() without __GFP_COMP flag. Such pages don't have refcount (page_count is 0) on tail pages, sending them by kernel_sendpage() may trigger a kernel panic from a corrupted kernel heap, because these pages are incorrectly freed in network stack as page_count 0 pages. This patch introduces a helper sendpage_ok(), it returns true if the checking page, - is not slab page: PageSlab(page) is false. - has page refcount: page_count(page) is not zero All drivers who want to send page to remote end by kernel_sendpage() may use this helper to check whether the page is OK. If the helper does not return true, the driver should try other non sendpage method (e.g. sock_no_sendpage()) to handle the page. Signed-off-by: Coly Li Cc: Chaitanya Kulkarni Cc: Christoph Hellwig Cc: Hannes Reinecke Cc: Jan Kara Cc: Jens Axboe Cc: Mikhail Skorzhinskii Cc: Philipp Reisner Cc: Sagi Grimberg Cc: Vlastimil Babka Cc: stable@vger.kernel.org --- Changelog: v4, change sendpage_ok() as an inline helper, and post it as separate patch. v3, introduce a more common sendpage_ok() v2, fix typo in patch subject v1, the initial version. include/linux/net.h | 15 +++++++++++++++ 1 file changed, 15 insertions(+) diff --git a/include/linux/net.h b/include/linux/net.h index d48ff1180879..97e8f1a8a427 100644 --- a/include/linux/net.h +++ b/include/linux/net.h @@ -286,6 +286,21 @@ do { \ #define net_get_random_once_wait(buf, nbytes) \ get_random_once_wait((buf), (nbytes)) +/* + * E.g. XFS meta- & log-data is in slab pages, or bcache meta + * data pages, or other high order pages allocated by + * __get_free_pages() without __GFP_COMP, which have a page_count + * of 0 and/or have PageSlab() set. We cannot use send_page for + * those, as that does get_page(); put_page(); and would cause + * either a VM_BUG directly, or __page_cache_release a page that + * would actually still be referenced by someone, leading to some + * obscure delayed Oops somewhere else. + */ +static inline bool sendpage_ok(struct page *page) +{ + return (!PageSlab(page) && page_count(page) >= 1); +} + int kernel_sendmsg(struct socket *sock, struct msghdr *msg, struct kvec *vec, size_t num, size_t len); int kernel_sendmsg_locked(struct sock *sk, struct msghdr *msg,