From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jeff Moyer Subject: Re: [PATCH 4/4] fs: Fix possible use-after-free with AIO Date: Wed, 23 Jan 2013 10:02:09 -0500 Message-ID: References: <1358945780-23661-1-git-send-email-jack@suse.cz> <1358945780-23661-5-git-send-email-jack@suse.cz> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: linux-fsdevel@vger.kernel.org, tytso@mit.edu, bpm@sgi.com, jlbec@evilplan.org, Christoph Hellwig , Jens Axboe , stable@vger.kernel.org To: Jan Kara Return-path: In-Reply-To: <1358945780-23661-5-git-send-email-jack@suse.cz> (Jan Kara's message of "Wed, 23 Jan 2013 13:56:20 +0100") Sender: stable-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org Jan Kara writes: > Running AIO is pinning inode in memory using file reference. Once AIO > is completed using aio_complete(), file reference is put and inode can > be freed from memory. So we have to be sure that calling aio_complete() > is the last thing we do with the inode. > > CC: Christoph Hellwig > CC: Jens Axboe > CC: Jeff Moyer > CC: stable@vger.kernel.org > Signed-off-by: Jan Kara > --- > fs/direct-io.c | 2 +- > 1 files changed, 1 insertions(+), 1 deletions(-) > > diff --git a/fs/direct-io.c b/fs/direct-io.c > index cf5b44b..f853263 100644 > --- a/fs/direct-io.c > +++ b/fs/direct-io.c > @@ -261,9 +261,9 @@ static ssize_t dio_complete(struct dio *dio, loff_t offset, ssize_t ret, bool is > dio->end_io(dio->iocb, offset, transferred, > dio->private, ret, is_async); > } else { > + inode_dio_done(dio->inode); > if (is_async) > aio_complete(dio->iocb, ret, 0); > - inode_dio_done(dio->inode); > } OK, so this is only a problem if nobody is waiting in inode_dio_wait, yes? Good catch, though it seems incredibly unlikely anyone would trip over this in practice (since fput is done in a worker thread, or deferred). Acked-by: Jeff Moyer