From patchwork Mon Jun 10 09:02:15 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ming Lei X-Patchwork-Id: 10984419 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id A7AE114C0 for ; Mon, 10 Jun 2019 09:02:38 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 990A5287AD for ; Mon, 10 Jun 2019 09:02:38 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 8D55D2884E; Mon, 10 Jun 2019 09:02:38 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 28C52287AD for ; Mon, 10 Jun 2019 09:02:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388601AbfFJJCh (ORCPT ); Mon, 10 Jun 2019 05:02:37 -0400 Received: from mx1.redhat.com ([209.132.183.28]:56928 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388190AbfFJJCh (ORCPT ); Mon, 10 Jun 2019 05:02:37 -0400 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id E0D0081DFC; Mon, 10 Jun 2019 09:02:36 +0000 (UTC) Received: from localhost (ovpn-8-22.pek2.redhat.com [10.72.8.22]) by smtp.corp.redhat.com (Postfix) with ESMTP id EAECC5C64D; Mon, 10 Jun 2019 09:02:33 +0000 (UTC) From: Ming Lei To: Jens Axboe Cc: linux-block@vger.kernel.org, Ming Lei , David Gibson , "Darrick J. Wong" , linux-xfs@vger.kernel.org, Alexander Viro , Christoph Hellwig Subject: [PATCH V3 2/2] block: fix page leak in case of merging to same page Date: Mon, 10 Jun 2019 17:02:15 +0800 Message-Id: <20190610090215.14412-3-ming.lei@redhat.com> In-Reply-To: <20190610090215.14412-1-ming.lei@redhat.com> References: <20190610090215.14412-1-ming.lei@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.25]); Mon, 10 Jun 2019 09:02:37 +0000 (UTC) Sender: linux-xfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-xfs@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Different iovec may use one same page, then 'pages' array filled by iov_iter_get_pages() may get reference of the same page several times. If some elements in 'pages' can be merged to same page in one bvec by bio_add_page(), bio_release_pages() only drops the page's reference once. This way causes page leak reported by David Gibson. This issue can be triggered since 576ed913 ("block: use bio_add_page in bio_iov_iter_get_pages"). Fixes the issue by putting the page's ref if it is merged to same page. Cc: David Gibson Cc: "Darrick J. Wong" Cc: linux-xfs@vger.kernel.org Cc: Alexander Viro Cc: Christoph Hellwig Link: https://lkml.org/lkml/2019/4/23/64 Fixes: 576ed913 ("block: use bio_add_page in bio_iov_iter_get_pages") Reported-by: David Gibson Signed-off-by: Ming Lei --- block/bio.c | 12 ++++++++++-- include/linux/bio.h | 8 ++++++++ 2 files changed, 18 insertions(+), 2 deletions(-) diff --git a/block/bio.c b/block/bio.c index 39e3b931dc3b..358ccb5086e6 100644 --- a/block/bio.c +++ b/block/bio.c @@ -652,6 +652,9 @@ static inline bool page_is_mergeable(const struct bio_vec *bv, return false; if (pfn_to_page(PFN_DOWN(vec_end_addr)) + 1 != page) return false; + /* drop page ref if the page has been added and user asks to do that */ + } else if (flags & BVEC_MERGE_PUT_SAME_PAGE) { + put_page(page); } WARN_ON_ONCE((flags & BVEC_MERGE_TO_SAME_PAGE) && @@ -924,8 +927,13 @@ static int __bio_iov_iter_get_pages(struct bio *bio, struct iov_iter *iter) struct page *page = pages[i]; len = min_t(size_t, PAGE_SIZE - offset, left); - if (WARN_ON_ONCE(bio_add_page(bio, page, len, offset) != len)) - return -EINVAL; + + if (!__bio_try_merge_page(bio, page, len, offset, + BVEC_MERGE_PUT_SAME_PAGE)) { + if (WARN_ON_ONCE(bio_full(bio))) + return -EINVAL; + __bio_add_page(bio, page, len, offset); + } offset = 0; } diff --git a/include/linux/bio.h b/include/linux/bio.h index ee18895431ba..0168bc5df8e4 100644 --- a/include/linux/bio.h +++ b/include/linux/bio.h @@ -428,6 +428,14 @@ enum bvec_merge_flags { * bvec */ BVEC_MERGE_TO_SAME_PAGE = BIT(0), + + /* + * put refcount of bio's last page if the start page to add is + * same with bio's last page. If user gets refcount of every + * page added to bio before calling bio_add_page, please consider + * to use this flag for avoiding page leak + */ + BVEC_MERGE_PUT_SAME_PAGE = BIT(1), }; extern int bio_add_page(struct bio *, struct page *, unsigned int,unsigned int);