From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:43815 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933345AbcA0RU7 (ORCPT ); Wed, 27 Jan 2016 12:20:59 -0500 Subject: Patch "direct-io: Fix negative return from dio read beyond eof" has been added to the 4.3-stable tree To: jack@suse.cz, avi@scylladb.com, axboe@fb.com, gregkh@linuxfoundation.org, swhiteho@redhat.com Cc: , From: Date: Wed, 27 Jan 2016 09:20:57 -0800 Message-ID: <145391525770128@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org List-ID: This is a note to let you know that I've just added the patch titled direct-io: Fix negative return from dio read beyond eof to the 4.3-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: direct-io-fix-negative-return-from-dio-read-beyond-eof.patch and it can be found in the queue-4.3 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let know about it. >>From 74cedf9b6c603f2278a05bc91b140b32b434d0b5 Mon Sep 17 00:00:00 2001 From: Jan Kara Date: Mon, 30 Nov 2015 10:15:42 -0700 Subject: direct-io: Fix negative return from dio read beyond eof From: Jan Kara commit 74cedf9b6c603f2278a05bc91b140b32b434d0b5 upstream. Assume a filesystem with 4KB blocks. When a file has size 1000 bytes and we issue direct IO read at offset 1024, blockdev_direct_IO() reads the tail of the last block and the logic for handling short DIO reads in dio_complete() results in a return value -24 (1000 - 1024) which obviously confuses userspace. Fix the problem by bailing out early once we sample i_size and can reliably check that direct IO read starts beyond i_size. Reported-by: Avi Kivity Fixes: 9fe55eea7e4b444bafc42fa0000cc2d1d2847275 CC: Steven Whitehouse Signed-off-by: Jan Kara Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman --- fs/direct-io.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) --- a/fs/direct-io.c +++ b/fs/direct-io.c @@ -1161,6 +1161,15 @@ do_blockdev_direct_IO(struct kiocb *iocb } } + /* Once we sampled i_size check for reads beyond EOF */ + dio->i_size = i_size_read(inode); + if (iov_iter_rw(iter) == READ && offset >= dio->i_size) { + if (dio->flags & DIO_LOCKING) + mutex_unlock(&inode->i_mutex); + kmem_cache_free(dio_cache, dio); + goto out; + } + /* * For file extending writes updating i_size before data writeouts * complete can expose uninitialized blocks in dumb filesystems. @@ -1214,7 +1223,6 @@ do_blockdev_direct_IO(struct kiocb *iocb sdio.next_block_for_io = -1; dio->iocb = iocb; - dio->i_size = i_size_read(inode); spin_lock_init(&dio->bio_lock); dio->refcount = 1; Patches currently in stable-queue which might be from jack@suse.cz are queue-4.3/direct-io-fix-negative-return-from-dio-read-beyond-eof.patch