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=-8.3 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,UNPARSEABLE_RELAY, USER_AGENT_SANE_1 autolearn=unavailable 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 88EABC43603 for ; Wed, 18 Dec 2019 19:24:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 45DD8206D7 for ; Wed, 18 Dec 2019 19:24:31 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=oracle.com header.i=@oracle.com header.b="bQbgh15G" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727406AbfLRTYZ (ORCPT ); Wed, 18 Dec 2019 14:24:25 -0500 Received: from aserp2120.oracle.com ([141.146.126.78]:60408 "EHLO aserp2120.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726824AbfLRTYZ (ORCPT ); Wed, 18 Dec 2019 14:24:25 -0500 Received: from pps.filterd (aserp2120.oracle.com [127.0.0.1]) by aserp2120.oracle.com (8.16.0.27/8.16.0.27) with SMTP id xBIJJJCH111940; Wed, 18 Dec 2019 19:23:39 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=date : from : to : cc : subject : message-id : references : mime-version : content-type : in-reply-to; s=corp-2019-08-05; bh=tnpSkD3PyQg3qyuFNzFdGihBE+SRwrl1WHntdclf1So=; b=bQbgh15Gu3DrbNQyfISBQ0I7Kgucxj4BTQ8Ap+lP6uWTFZc0lF4+svBD9FWNQfGBmuxI HrT8zom004Ud0YaXW5BBuU0gLcuJCsCuUKZwSOI3/hP9MP3ZuPIn9o/BTKJN7b2T3asa /vVVhtXgpkYMsN4s8wBnrEgdRYcqCp4OoTRnXMZ+kgkwir2YFfyfe1MHzQ9FeFI5irPH HvJohIJg1BmIIOe3CW0FDyDaTNcLwZGTdl40ADmcXAXqTGeMoi8dCHDcrbO134RroVPC eNE+LkufaIYI3bHVt6lBM1oRkkHFK7ahrYgIBOWGWBcH1GZQlzmi7f9OG4Q/Rfrh68fa Jg== Received: from aserp3020.oracle.com (aserp3020.oracle.com [141.146.126.70]) by aserp2120.oracle.com with ESMTP id 2wvqpqfq24-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Wed, 18 Dec 2019 19:23:39 +0000 Received: from pps.filterd (aserp3020.oracle.com [127.0.0.1]) by aserp3020.oracle.com (8.16.0.27/8.16.0.27) with SMTP id xBIJJFGF108432; Wed, 18 Dec 2019 19:23:39 GMT Received: from userv0122.oracle.com (userv0122.oracle.com [156.151.31.75]) by aserp3020.oracle.com with ESMTP id 2wyp4y0082-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Wed, 18 Dec 2019 19:23:38 +0000 Received: from abhmp0005.oracle.com (abhmp0005.oracle.com [141.146.116.11]) by userv0122.oracle.com (8.14.4/8.14.4) with ESMTP id xBIJNYnO020087; Wed, 18 Dec 2019 19:23:34 GMT Received: from localhost (/67.169.218.210) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Wed, 18 Dec 2019 11:23:34 -0800 Date: Wed, 18 Dec 2019 11:23:31 -0800 From: "Darrick J. Wong" To: Andreas Gruenbacher Cc: Alexander Viro , Christoph Hellwig , Linus Torvalds , LKML , Jeff Layton , Sage Weil , Ilya Dryomov , "Theodore Ts'o" , Andreas Dilger , Jaegeuk Kim , Chao Yu , linux-xfs@vger.kernel.org, linux-fsdevel , Richard Weinberger , Artem Bityutskiy , Adrian Hunter , Ceph Development , linux-ext4 , linux-f2fs-devel@lists.sourceforge.net, linux-mtd@lists.infradead.org, Chris Mason , Josef Bacik , David Sterba , linux-btrfs@vger.kernel.org, Jan Kara Subject: Re: [PATCH v3] fs: Fix page_mkwrite off-by-one errors Message-ID: <20191218192331.GA7473@magnolia> References: <20191218130935.32402-1-agruenba@redhat.com> <20191218185216.GA7497@magnolia> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.9.4 (2018-02-28) X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9475 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=0 malwarescore=0 phishscore=0 bulkscore=0 spamscore=0 mlxscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1911140001 definitions=main-1912180150 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9475 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1911140001 definitions=main-1912180150 Sender: linux-ext4-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-ext4@vger.kernel.org On Wed, Dec 18, 2019 at 08:15:36PM +0100, Andreas Gruenbacher wrote: > On Wed, Dec 18, 2019 at 7:55 PM Darrick J. Wong wrote: > > On Wed, Dec 18, 2019 at 02:09:35PM +0100, Andreas Gruenbacher wrote: > > > Hi Darrick, > > > > > > can this fix go in via the xfs tree? > > > > Er, I'd rather not touch five other filesystems via the XFS tree. > > However, a more immediate problem that I think I see is... > > > > > Thanks, > > > Andreas > > > > > > -- > > > > > > The check in block_page_mkwrite that is meant to determine whether an > > > offset is within the inode size is off by one. This bug has been copied > > > into iomap_page_mkwrite and several filesystems (ubifs, ext4, f2fs, > > > ceph). > > > > > > Fix that by introducing a new page_mkwrite_check_truncate helper that > > > checks for truncate and computes the bytes in the page up to EOF. Use > > > the helper in the above mentioned filesystems. > > > > > > In addition, use the new helper in btrfs as well. > > > > > > Signed-off-by: Andreas Gruenbacher > > > Acked-by: David Sterba (btrfs part) > > > Acked-by: Richard Weinberger (ubifs part) > > > --- > > > fs/btrfs/inode.c | 15 ++++----------- > > > fs/buffer.c | 16 +++------------- > > > fs/ceph/addr.c | 2 +- > > > fs/ext4/inode.c | 14 ++++---------- > > > fs/f2fs/file.c | 19 +++++++------------ > > > fs/iomap/buffered-io.c | 18 +++++------------- > > > fs/ubifs/file.c | 3 +-- > > > include/linux/pagemap.h | 28 ++++++++++++++++++++++++++++ > > > 8 files changed, 53 insertions(+), 62 deletions(-) > > > > > > diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c > > > index 56032c518b26..86c6fcd8139d 100644 > > > --- a/fs/btrfs/inode.c > > > +++ b/fs/btrfs/inode.c > > > @@ -9016,13 +9016,11 @@ vm_fault_t btrfs_page_mkwrite(struct vm_fault *vmf) > > > ret = VM_FAULT_NOPAGE; /* make the VM retry the fault */ > > > again: > > > lock_page(page); > > > - size = i_size_read(inode); > > > > > > - if ((page->mapping != inode->i_mapping) || > > > - (page_start >= size)) { > > > - /* page got truncated out from underneath us */ > > > + ret2 = page_mkwrite_check_truncate(page, inode); > > > + if (ret2 < 0) > > > goto out_unlock; > > > > ...here we try to return -EFAULT as vm_fault_t. Notice how btrfs returns > > VM_FAULT_* values directly and never calls block_page_mkwrite_return? I > > know dsterba acked this, but I cannot see how this is correct? > > Well, page_mkwrite_check_truncate can only fail with -EFAULT, in which > case btrfs_page_mkwrite will return VM_FAULT_NOPAGE. It would be > cleaner not to discard page_mkwrite_check_truncate's return value > though. *OH*, because we're stuffing the value in ret2, not ret. Ok, that makes more sense. Er, I guess I don't mind pushing via iomap tree, but could we get some acks from Ted and any of the ceph maintainers? --D > > > - } > > > + zero_start = ret2; > > > wait_on_page_writeback(page); > > > > > > lock_extent_bits(io_tree, page_start, page_end, &cached_state); > > > @@ -9043,6 +9041,7 @@ vm_fault_t btrfs_page_mkwrite(struct vm_fault *vmf) > > > goto again; > > > } > > > > > > + size = i_size_read(inode); > > > if (page->index == ((size - 1) >> PAGE_SHIFT)) { > > > reserved_space = round_up(size - page_start, > > > fs_info->sectorsize); > > > @@ -9075,12 +9074,6 @@ vm_fault_t btrfs_page_mkwrite(struct vm_fault *vmf) > > > } > > > ret2 = 0; > > > > > > - /* page is wholly or partially inside EOF */ > > > - if (page_start + PAGE_SIZE > size) > > > - zero_start = offset_in_page(size); > > > - else > > > - zero_start = PAGE_SIZE; > > > - > > > if (zero_start != PAGE_SIZE) { > > > kaddr = kmap(page); > > > memset(kaddr + zero_start, 0, PAGE_SIZE - zero_start); > > > diff --git a/fs/buffer.c b/fs/buffer.c > > > index d8c7242426bb..53aabde57ca7 100644 > > > --- a/fs/buffer.c > > > +++ b/fs/buffer.c > > > @@ -2499,23 +2499,13 @@ int block_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf, > > > struct page *page = vmf->page; > > > struct inode *inode = file_inode(vma->vm_file); > > > unsigned long end; > > > - loff_t size; > > > int ret; > > > > > > lock_page(page); > > > - size = i_size_read(inode); > > > - if ((page->mapping != inode->i_mapping) || > > > - (page_offset(page) > size)) { > > > - /* We overload EFAULT to mean page got truncated */ > > > - ret = -EFAULT; > > > + ret = page_mkwrite_check_truncate(page, inode); > > > + if (ret < 0) > > > goto out_unlock; > > > - } > > > - > > > - /* page is wholly or partially inside EOF */ > > > - if (((page->index + 1) << PAGE_SHIFT) > size) > > > - end = size & ~PAGE_MASK; > > > - else > > > - end = PAGE_SIZE; > > > + end = ret; > > > > > > ret = __block_write_begin(page, 0, end, get_block); > > > if (!ret) > > > diff --git a/fs/ceph/addr.c b/fs/ceph/addr.c > > > index 7ab616601141..ef958aa4adb4 100644 > > > --- a/fs/ceph/addr.c > > > +++ b/fs/ceph/addr.c > > > @@ -1575,7 +1575,7 @@ static vm_fault_t ceph_page_mkwrite(struct vm_fault *vmf) > > > do { > > > lock_page(page); > > > > > > - if ((off > size) || (page->mapping != inode->i_mapping)) { > > > + if (page_mkwrite_check_truncate(page, inode) < 0) { > > > unlock_page(page); > > > ret = VM_FAULT_NOPAGE; > > > break; > > > diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c > > > index 28f28de0c1b6..51ab1d2cac80 100644 > > > --- a/fs/ext4/inode.c > > > +++ b/fs/ext4/inode.c > > > @@ -5871,7 +5871,6 @@ vm_fault_t ext4_page_mkwrite(struct vm_fault *vmf) > > > { > > > struct vm_area_struct *vma = vmf->vma; > > > struct page *page = vmf->page; > > > - loff_t size; > > > unsigned long len; > > > int err; > > > vm_fault_t ret; > > > @@ -5907,18 +5906,13 @@ vm_fault_t ext4_page_mkwrite(struct vm_fault *vmf) > > > } > > > > > > lock_page(page); > > > - size = i_size_read(inode); > > > - /* Page got truncated from under us? */ > > > - if (page->mapping != mapping || page_offset(page) > size) { > > > + err = page_mkwrite_check_truncate(page, inode); > > > + if (err < 0) { > > > unlock_page(page); > > > - ret = VM_FAULT_NOPAGE; > > > - goto out; > > > + goto out_ret; > > > } > > > + len = err; > > > > > > - if (page->index == size >> PAGE_SHIFT) > > > - len = size & ~PAGE_MASK; > > > - else > > > - len = PAGE_SIZE; > > > /* > > > * Return if we have all the buffers mapped. This avoids the need to do > > > * journal_start/journal_stop which can block and take a long time > > > diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c > > > index 85af112e868d..0e77b2e6f873 100644 > > > --- a/fs/f2fs/file.c > > > +++ b/fs/f2fs/file.c > > > @@ -51,7 +51,7 @@ static vm_fault_t f2fs_vm_page_mkwrite(struct vm_fault *vmf) > > > struct inode *inode = file_inode(vmf->vma->vm_file); > > > struct f2fs_sb_info *sbi = F2FS_I_SB(inode); > > > struct dnode_of_data dn = { .node_changed = false }; > > > - int err; > > > + int offset, err; > > > > > > if (unlikely(f2fs_cp_error(sbi))) { > > > err = -EIO; > > > @@ -70,13 +70,14 @@ static vm_fault_t f2fs_vm_page_mkwrite(struct vm_fault *vmf) > > > file_update_time(vmf->vma->vm_file); > > > down_read(&F2FS_I(inode)->i_mmap_sem); > > > lock_page(page); > > > - if (unlikely(page->mapping != inode->i_mapping || > > > - page_offset(page) > i_size_read(inode) || > > > - !PageUptodate(page))) { > > > + err = -EFAULT; > > > + if (likely(PageUptodate(page))) > > > + err = page_mkwrite_check_truncate(page, inode); > > > + if (unlikely(err < 0)) { > > > unlock_page(page); > > > - err = -EFAULT; > > > goto out_sem; > > > } > > > + offset = err; > > > > > > /* block allocation */ > > > __do_map_lock(sbi, F2FS_GET_BLOCK_PRE_AIO, true); > > > @@ -101,14 +102,8 @@ static vm_fault_t f2fs_vm_page_mkwrite(struct vm_fault *vmf) > > > if (PageMappedToDisk(page)) > > > goto out_sem; > > > > > > - /* page is wholly or partially inside EOF */ > > > - if (((loff_t)(page->index + 1) << PAGE_SHIFT) > > > > - i_size_read(inode)) { > > > - loff_t offset; > > > - > > > - offset = i_size_read(inode) & ~PAGE_MASK; > > > + if (offset != PAGE_SIZE) > > > zero_user_segment(page, offset, PAGE_SIZE); > > > - } > > > set_page_dirty(page); > > > if (!PageUptodate(page)) > > > SetPageUptodate(page); > > > diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c > > > index d33c7bc5ee92..1aaf157fd6e9 100644 > > > --- a/fs/iomap/buffered-io.c > > > +++ b/fs/iomap/buffered-io.c > > > @@ -1062,24 +1062,16 @@ vm_fault_t iomap_page_mkwrite(struct vm_fault *vmf, const struct iomap_ops *ops) > > > struct page *page = vmf->page; > > > struct inode *inode = file_inode(vmf->vma->vm_file); > > > unsigned long length; > > > - loff_t offset, size; > > > + loff_t offset; > > > ssize_t ret; > > > > > > lock_page(page); > > > - size = i_size_read(inode); > > > - offset = page_offset(page); > > > - if (page->mapping != inode->i_mapping || offset > size) { > > > - /* We overload EFAULT to mean page got truncated */ > > > - ret = -EFAULT; > > > + ret = page_mkwrite_check_truncate(page, inode); > > > + if (ret < 0) > > > goto out_unlock; > > > - } > > > - > > > - /* page is wholly or partially inside EOF */ > > > - if (offset > size - PAGE_SIZE) > > > - length = offset_in_page(size); > > > - else > > > - length = PAGE_SIZE; > > > + length = ret; > > > > > > + offset = page_offset(page); > > > while (length > 0) { > > > ret = iomap_apply(inode, offset, length, > > > IOMAP_WRITE | IOMAP_FAULT, ops, page, > > > diff --git a/fs/ubifs/file.c b/fs/ubifs/file.c > > > index cd52585c8f4f..91f7a1f2db0d 100644 > > > --- a/fs/ubifs/file.c > > > +++ b/fs/ubifs/file.c > > > @@ -1563,8 +1563,7 @@ static vm_fault_t ubifs_vm_page_mkwrite(struct vm_fault *vmf) > > > } > > > > > > lock_page(page); > > > - if (unlikely(page->mapping != inode->i_mapping || > > > - page_offset(page) > i_size_read(inode))) { > > > + if (unlikely(page_mkwrite_check_truncate(page, inode) < 0)) { > > > /* Page got truncated out from underneath us */ > > > goto sigbus; > > > } > > > diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h > > > index 37a4d9e32cd3..ccb14b6a16b5 100644 > > > --- a/include/linux/pagemap.h > > > +++ b/include/linux/pagemap.h > > > @@ -636,4 +636,32 @@ static inline unsigned long dir_pages(struct inode *inode) > > > PAGE_SHIFT; > > > } > > > > > > +/** > > > + * page_mkwrite_check_truncate - check if page was truncated > > > + * @page: the page to check > > > + * @inode: the inode to check the page against > > > + * > > > + * Returns the number of bytes in the page up to EOF, > > > + * or -EFAULT if the page was truncated. > > > + */ > > > +static inline int page_mkwrite_check_truncate(struct page *page, > > > + struct inode *inode) > > > +{ > > > + loff_t size = i_size_read(inode); > > > + pgoff_t index = size >> PAGE_SHIFT; > > > + int offset = offset_in_page(size); > > > + > > > + if (page->mapping != inode->i_mapping) > > > + return -EFAULT; > > > + > > > + /* page is wholly inside EOF */ > > > + if (page->index < index) > > > + return PAGE_SIZE; > > > + /* page is wholly past EOF */ > > > + if (page->index > index || !offset) > > > + return -EFAULT; > > > + /* page is partially inside EOF */ > > > + return offset; > > > +} > > > + > > > #endif /* _LINUX_PAGEMAP_H */ > > > -- > > > 2.20.1 > > > > > >