Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752250AbdFAPpK (ORCPT ); Thu, 1 Jun 2017 11:45:10 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:33363 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752180AbdFAPpD (ORCPT ); Thu, 1 Jun 2017 11:45:03 -0400 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "Jan Kara" , "Al Viro" , "Theodore Ts'o" Date: Thu, 01 Jun 2017 16:43:16 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.16 082/212] ext4: fix data corruption in data=journal mode In-Reply-To: X-SA-Exim-Connect-IP: 82.70.136.246 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2425 Lines: 71 3.16.44-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Jan Kara commit 3b136499e906460919f0d21a49db1aaccf0ae963 upstream. ext4_journalled_write_end() did not propely handle all the cases when generic_perform_write() did not copy all the data into the target page and could mark buffers with uninitialized contents as uptodate and dirty leading to possible data corruption (which would be quickly fixed by generic_perform_write() retrying the write but still). Fix the problem by carefully handling the case when the page that is written to is not uptodate. Reported-by: Al Viro Signed-off-by: Jan Kara Signed-off-by: Theodore Ts'o Signed-off-by: Ben Hutchings --- fs/ext4/inode.c | 23 +++++++++++++---------- 1 file changed, 13 insertions(+), 10 deletions(-) --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -1171,7 +1171,9 @@ errout: * set the buffer to be dirty, since in data=journalled mode we need * to call ext4_handle_dirty_metadata() instead. */ -static void zero_new_buffers(struct page *page, unsigned from, unsigned to) +static void ext4_journalled_zero_new_buffers(handle_t *handle, + struct page *page, + unsigned from, unsigned to) { unsigned int block_start = 0, block_end; struct buffer_head *head, *bh; @@ -1188,7 +1190,7 @@ static void zero_new_buffers(struct page size = min(to, block_end) - start; zero_user(page, start, size); - set_buffer_uptodate(bh); + write_end_fn(handle, bh); } clear_buffer_new(bh); } @@ -1219,15 +1221,16 @@ static int ext4_journalled_write_end(str if (ext4_has_inline_data(inode)) copied = ext4_write_inline_data_end(inode, pos, len, copied, page); - else { - if (copied < len) { - if (!PageUptodate(page)) - copied = 0; - zero_new_buffers(page, from+copied, to); - } - + else if (unlikely(copied < len) && !PageUptodate(page)) { + copied = 0; + ext4_journalled_zero_new_buffers(handle, page, from, to); + } else { + if (unlikely(copied < len)) + ext4_journalled_zero_new_buffers(handle, page, + from + copied, to); ret = ext4_walk_page_buffers(handle, page_buffers(page), from, - to, &partial, write_end_fn); + from + copied, &partial, + write_end_fn); if (!partial) SetPageUptodate(page); }