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=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, 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 A8505C2D0C3 for ; Wed, 18 Dec 2019 14:10:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 70D7F2176D for ; Wed, 18 Dec 2019 14:10:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727174AbfLROKV (ORCPT ); Wed, 18 Dec 2019 09:10:21 -0500 Received: from mx2.suse.de ([195.135.220.15]:38380 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727027AbfLROKU (ORCPT ); Wed, 18 Dec 2019 09:10:20 -0500 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx2.suse.de (Postfix) with ESMTP id ED888AC2F; Wed, 18 Dec 2019 14:10:15 +0000 (UTC) Received: by quack2.suse.cz (Postfix, from userid 1000) id ED2BF1E0B2D; Wed, 18 Dec 2019 15:10:12 +0100 (CET) Date: Wed, 18 Dec 2019 15:10:12 +0100 From: Jan Kara To: Andreas Gruenbacher Cc: "Darrick J. Wong" , Alexander Viro , Christoph Hellwig , Linus Torvalds , linux-kernel@vger.kernel.org, Jeff Layton , Sage Weil , Ilya Dryomov , Theodore Ts'o , Andreas Dilger , Jaegeuk Kim , Chao Yu , linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, Richard Weinberger , Artem Bityutskiy , Adrian Hunter , ceph-devel@vger.kernel.org, linux-ext4@vger.kernel.org, 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: <20191218141012.GD19387@quack2.suse.cz> References: <20191218130935.32402-1-agruenba@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20191218130935.32402-1-agruenba@redhat.com> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-xfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-xfs@vger.kernel.org On Wed 18-12-19 14:09:35, Andreas Gruenbacher wrote: > Hi Darrick, > > can this fix go in via the xfs tree? > > 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) The patch looks good to me (didn't really check btrfs). I'd just note that page_mkwrite_check_truncate() doesn't seem that small to be worth inlining... Other than that feel free to add: Reviewed-by: Jan Kara Honza > --- > 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; > - } > + 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 > -- Jan Kara SUSE Labs, CR