Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752688AbdFHAAx (ORCPT ); Wed, 7 Jun 2017 20:00:53 -0400 Received: from wtarreau.pck.nerim.net ([62.212.114.60]:50283 "EHLO 1wt.eu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752472AbdFGXDA (ORCPT ); Wed, 7 Jun 2017 19:03:00 -0400 From: Willy Tarreau To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, linux@roeck-us.net Cc: Robert Doebbelin , Miklos Szeredi , Jan Kara , Willy Tarreau Subject: [PATCH 3.10 105/250] fuse: do not use iocb after it may have been freed Date: Thu, 8 Jun 2017 00:58:11 +0200 Message-Id: <1496876436-32402-106-git-send-email-w@1wt.eu> X-Mailer: git-send-email 2.8.0.rc2.1.gbe9624a In-Reply-To: <1496876436-32402-1-git-send-email-w@1wt.eu> References: <1496876436-32402-1-git-send-email-w@1wt.eu> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1939 Lines: 54 From: Robert Doebbelin commit 7cabc61e01a0a8b663bd2b4c982aa53048218734 upstream. There's a race in fuse_direct_IO(), whereby is_sync_kiocb() is called on an iocb that could have been freed if async io has already completed. The fix in this case is simple and obvious: cache the result before starting io. It was discovered by KASan: Kernel: ================================================================== Kernel: BUG: KASan: use after free in fuse_direct_IO+0xb1a/0xcc0 at addr ffff88036c414390 Signed-off-by: Robert Doebbelin Signed-off-by: Miklos Szeredi Fixes: bcba24ccdc82 ("fuse: enable asynchronous processing direct IO") Signed-off-by: Jan Kara Signed-off-by: Willy Tarreau --- fs/fuse/file.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/fs/fuse/file.c b/fs/fuse/file.c index 35f604b..7ada0f0 100644 --- a/fs/fuse/file.c +++ b/fs/fuse/file.c @@ -2398,6 +2398,7 @@ fuse_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov, loff_t i_size; size_t count = iov_length(iov, nr_segs); struct fuse_io_priv *io; + bool is_sync = is_sync_kiocb(iocb); pos = offset; inode = file->f_mapping->host; @@ -2433,7 +2434,7 @@ fuse_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov, * to wait on real async I/O requests, so we must submit this request * synchronously. */ - if (!is_sync_kiocb(iocb) && (offset + count > i_size) && rw == WRITE) + if (!is_sync && (offset + count > i_size) && rw == WRITE) io->async = false; if (rw == WRITE) @@ -2445,7 +2446,7 @@ fuse_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov, fuse_aio_complete(io, ret < 0 ? ret : 0, -1); /* we have a non-extending, async request, so return */ - if (!is_sync_kiocb(iocb)) + if (!is_sync) return -EIOCBQUEUED; ret = wait_on_sync_kiocb(iocb); -- 2.8.0.rc2.1.gbe9624a