From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754427AbdBOXOg (ORCPT ); Wed, 15 Feb 2017 18:14:36 -0500 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:53697 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754394AbdBOXOd (ORCPT ); Wed, 15 Feb 2017 18:14:33 -0500 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, "Miklos Szeredi" , "Al Viro" Date: Wed, 15 Feb 2017 22:41:40 +0000 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.16 230/306] fuse: fix fuse_write_end() if zero bytes were copied In-Reply-To: X-SA-Exim-Connect-IP: 2a02:8011:400e:2:6f00:88c8:c921:d332 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 3.16.40-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Miklos Szeredi commit 59c3b76cc61d1d676f965c192cc7969aa5cb2744 upstream. If pos is at the beginning of a page and copied is zero then page is not zeroed but is marked uptodate. Fix by skipping everything except unlock/put of page if zero bytes were copied. Reported-by: Al Viro Fixes: 6b12c1b37e55 ("fuse: Implement write_begin/write_end callbacks") Signed-off-by: Miklos Szeredi Signed-off-by: Ben Hutchings --- fs/fuse/file.c | 6 ++++++ 1 file changed, 6 insertions(+) --- a/fs/fuse/file.c +++ b/fs/fuse/file.c @@ -2058,6 +2058,10 @@ static int fuse_write_end(struct file *f { struct inode *inode = page->mapping->host; + /* Haven't copied anything? Skip zeroing, size extending, dirtying. */ + if (!copied) + goto unlock; + if (!PageUptodate(page)) { /* Zero any unwritten bytes at the end of the page */ size_t endoff = (pos + copied) & ~PAGE_CACHE_MASK; @@ -2068,6 +2072,8 @@ static int fuse_write_end(struct file *f fuse_write_update_size(inode, pos + copied); set_page_dirty(page); + +unlock: unlock_page(page); page_cache_release(page);