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From: Christoph Hellwig <hch@lst.de>
To: viro@zeniv.linux.org.uk
Cc: Avi Kivity <avi@scylladb.com>,
	linux-aio@kvack.org, linux-fsdevel@vger.kernel.org,
	netdev@vger.kernel.org, linux-api@vger.kernel.org,
	linux-kernel@vger.kernel.org, stable@kernel.org
Subject: [PATCH 01/33] fix io_destroy()/aio_complete() race
Date: Wed, 23 May 2018 21:19:50 +0200	[thread overview]
Message-ID: <20180523192022.1703-2-hch@lst.de> (raw)
In-Reply-To: <20180523192022.1703-1-hch@lst.de>

From: Al Viro <viro@zeniv.linux.org.uk>

If io_destroy() gets to cancelling everything that can be cancelled and
gets to kiocb_cancel() calling the function driver has left in ->ki_cancel,
it becomes vulnerable to a race with IO completion.  At that point req
is already taken off the list and aio_complete() does *NOT* spin until
we (in free_ioctx_users()) releases ->ctx_lock.  As the result, it proceeds
to kiocb_free(), freing req just it gets passed to ->ki_cancel().

Fix is simple - remove from the list after the call of kiocb_cancel().  All
instances of ->ki_cancel() already have to cope with the being called with
iocb still on list - that's what happens in io_cancel(2).

Cc: stable@kernel.org
Fixes: 0460fef2a921 "aio: use cancellation list lazily"
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 fs/aio.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/fs/aio.c b/fs/aio.c
index 755d3f57bcc8..1c383bb44b2d 100644
--- a/fs/aio.c
+++ b/fs/aio.c
@@ -639,9 +639,8 @@ static void free_ioctx_users(struct percpu_ref *ref)
 	while (!list_empty(&ctx->active_reqs)) {
 		req = list_first_entry(&ctx->active_reqs,
 				       struct aio_kiocb, ki_list);
-
-		list_del_init(&req->ki_list);
 		kiocb_cancel(req);
+		list_del_init(&req->ki_list);
 	}
 
 	spin_unlock_irq(&ctx->ctx_lock);
-- 
2.17.0

  reply	other threads:[~2018-05-23 19:20 UTC|newest]

Thread overview: 72+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-05-23 19:19 aio poll and a new in-kernel poll API V13 Christoph Hellwig
2018-05-23 19:19 ` Christoph Hellwig [this message]
2018-05-23 19:19 ` [PATCH 02/33] uapi: turn __poll_t sparse checkin on by default Christoph Hellwig
2018-05-23 19:19 ` [PATCH 03/33] fs: unexport poll_schedule_timeout Christoph Hellwig
2018-05-23 19:19 ` [PATCH 04/33] fs: cleanup do_pollfd Christoph Hellwig
2018-05-23 19:19 ` [PATCH 05/33] fs: update documentation to mention __poll_t and match the code Christoph Hellwig
2018-05-23 19:19 ` [PATCH 06/33] fs: add new vfs_poll and file_can_poll helpers Christoph Hellwig
2018-05-23 19:19 ` [PATCH 07/33] fs: introduce new ->get_poll_head and ->poll_mask methods Christoph Hellwig
2018-05-23 19:19 ` [PATCH 08/33] aio: simplify KIOCB_KEY handling Christoph Hellwig
2018-05-23 19:19 ` [PATCH 09/33] aio: simplify cancellation Christoph Hellwig
2018-05-23 19:19 ` [PATCH 10/33] aio: implement IOCB_CMD_POLL Christoph Hellwig
2018-05-23 19:20 ` [PATCH 11/33] aio: try to complete poll iocbs without context switch Christoph Hellwig
2018-05-23 19:20 ` [PATCH 12/33] net: refactor socket_poll Christoph Hellwig
2018-05-23 19:20 ` [PATCH 13/33] net: add support for ->poll_mask in proto_ops Christoph Hellwig
2018-05-23 19:20 ` [PATCH 14/33] net: remove sock_no_poll Christoph Hellwig
2018-05-23 19:20 ` [PATCH 15/33] net/tcp: convert to ->poll_mask Christoph Hellwig
2018-05-23 19:20 ` [PATCH 16/33] net/unix: " Christoph Hellwig
2018-05-23 19:20 ` [PATCH 17/33] net: convert datagram_poll users tp ->poll_mask Christoph Hellwig
2018-05-23 19:20 ` [PATCH 18/33] net/dccp: convert to ->poll_mask Christoph Hellwig
2018-05-23 19:20 ` [PATCH 19/33] net/atm: " Christoph Hellwig
2018-05-23 19:20 ` [PATCH 20/33] net/vmw_vsock: " Christoph Hellwig
2018-05-23 19:20 ` [PATCH 21/33] net/tipc: " Christoph Hellwig
2018-05-23 19:20 ` [PATCH 22/33] net/sctp: " Christoph Hellwig
2018-05-23 19:20 ` [PATCH 23/33] net/bluetooth: " Christoph Hellwig
2018-05-23 19:20 ` [PATCH 24/33] net/caif: " Christoph Hellwig
2018-05-23 19:20 ` [PATCH 25/33] net/nfc: " Christoph Hellwig
2018-05-23 19:20 ` [PATCH 26/33] net/phonet: " Christoph Hellwig
2018-05-23 19:20 ` [PATCH 27/33] net/iucv: " Christoph Hellwig
2018-05-23 19:20 ` [PATCH 28/33] net/rxrpc: " Christoph Hellwig
2018-05-23 19:20 ` [PATCH 29/33] crypto: af_alg: " Christoph Hellwig
2018-05-23 19:20 ` [PATCH 30/33] pipe: " Christoph Hellwig
2018-05-23 19:20 ` [PATCH 31/33] eventfd: switch " Christoph Hellwig
2018-05-23 19:20 ` [PATCH 32/33] timerfd: convert " Christoph Hellwig
2018-05-23 19:20 ` [PATCH 33/33] random: " Christoph Hellwig
2018-05-26  0:11 ` aio poll and a new in-kernel poll API V13 Al Viro
2018-05-26  7:09   ` Al Viro
2018-05-26  7:23     ` Christoph Hellwig
2018-05-27 22:27       ` Al Viro
2018-05-27 22:28         ` [PATCH 1/4] aio: all callers of aio_{read,write,fsync,poll} treat 0 and -EIOCBQUEUED the same way Al Viro
2018-05-27 22:28           ` [PATCH 2/4] aio_read_events_ring(): make a bit more readable Al Viro
2018-05-27 22:28           ` [PATCH 3/4] aio: shift copyin of iocb into io_submit_one() Al Viro
2018-05-28  5:16             ` Christoph Hellwig
2018-05-27 22:28           ` [PATCH 4/4] aio: fold do_io_submit() into callers Al Viro
2018-05-27 23:14             ` Al Viro
2018-05-28  5:24               ` Christoph Hellwig
2018-05-28  5:15           ` [PATCH 1/4] aio: all callers of aio_{read,write,fsync,poll} treat 0 and -EIOCBQUEUED the same way Christoph Hellwig
2018-05-28 14:04             ` Al Viro
2018-05-28 17:54               ` Al Viro
2018-05-28 17:57                 ` [PATCH v2 1/6] aio: take list removal to (some) callers of aio_complete() Al Viro
2018-05-28 17:57                   ` [PATCH v2 2/6] aio: all callers of aio_{read,write,fsync,poll} treat 0 and -EIOCBQUEUED the same way Al Viro
2018-05-29  6:08                     ` Christoph Hellwig
2018-05-28 17:57                   ` [PATCH v2 3/6] aio_read_events_ring(): make a bit more readable Al Viro
2018-05-28 17:57                   ` [PATCH v2 4/6] aio: shift copyin of iocb into io_submit_one() Al Viro
2018-05-28 17:57                   ` [PATCH v2 5/6] aio: fold do_io_submit() into callers Al Viro
2018-05-29  6:10                     ` Christoph Hellwig
2018-05-28 17:57                   ` [PATCH v2 6/6] aio: sanitize the limit checking in io_submit(2) Al Viro
2018-05-29  6:10                     ` Christoph Hellwig
2018-05-29  6:08                   ` [PATCH v2 1/6] aio: take list removal to (some) callers of aio_complete() Christoph Hellwig
2018-05-28 22:20                 ` [PATCH 1/4] vmsplice: lift import_iovec() into do_vmsplice() Al Viro
2018-05-28 22:20                   ` [PATCH 2/4] vmsplice(): lift importing iovec into vmsplice(2) and compat counterpart Al Viro
2018-05-28 22:20                   ` [PATCH 3/4] signalfd: lift sigmask copyin and size checks to callers of do_signalfd4() Al Viro
2018-05-28 22:20                   ` [PATCH 4/4] orangefs: simplify compat ioctl handling Al Viro
2018-05-31 11:11                     ` kbuild test robot
2018-05-31 20:54                     ` Mike Marshall
2018-05-31 21:03                       ` Al Viro
2018-06-01 21:13                         ` Mike Marshall
2018-06-06 22:57                   ` [1/4] vmsplice: lift import_iovec() into do_vmsplice() Andrei Vagin
2018-06-07 17:56                     ` Andrei Vagin
2018-06-11 20:14                       ` Cyrill Gorcunov
2018-06-11 20:16                         ` Al Viro
2018-06-11 20:18                           ` Cyrill Gorcunov
2018-06-14 22:22                           ` Andrey Vagin

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