From: Al Viro <viro@zeniv.linux.org.uk>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Eric Dumazet <eric.dumazet@gmail.com>,
David Miller <davem@davemloft.net>,
Jason Baron <jbaron@akamai.com>,
kgraul@linux.ibm.com, ktkhai@virtuozzo.com,
kyeongdon.kim@lge.com,
Linux List Kernel Mailing <linux-kernel@vger.kernel.org>,
Netdev <netdev@vger.kernel.org>,
pabeni@redhat.com, syzkaller-bugs@googlegroups.com,
xiyou.wangcong@gmail.com, Christoph Hellwig <hch@lst.de>,
zhengbin <zhengbin13@huawei.com>,
bcrl@kvack.org, linux-fsdevel@vger.kernel.org,
linux-aio@kvack.org, houtao1@huawei.com, yi.zhang@huawei.com
Subject: Re: [PATCH 2/8] aio_poll_wake(): don't set ->woken if we ignore the wakeup
Date: Thu, 7 Mar 2019 02:18:44 +0000 [thread overview]
Message-ID: <20190307021844.GC2217@ZenIV.linux.org.uk> (raw)
In-Reply-To: <20190307000316.31133-2-viro@ZenIV.linux.org.uk>
On Thu, Mar 07, 2019 at 12:03:10AM +0000, Al Viro wrote:
> From: Al Viro <viro@zeniv.linux.org.uk>
>
> In case of early wakeups, aio_poll() assumes that aio_poll_complete()
> has either already happened or is imminent. In that case we do not
> want to put iocb on the list of cancellables. However, ignored
> wakeups need to be treated as if wakeup has not happened at all.
> Trivially fixed by having aio_poll_wake() set ->woken only after
> it's committed to taking iocb out of the waitqueue.
>
> Spotted-by: zhengbin <zhengbin13@huawei.com>
> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
... and unfortunately it's worse than just that - what both of us
have missed is that one could have non-specific wakep + schedule_work +
aio_poll_complete_work() rechecking ->poll(), seeing nothing of
interest and reinserting into queue. All before vfs_poll() manages
to return into aio_poll(). The window is harder to hit, but it's
still there, with exact same "failed to add to cancel list" kind of bug
if we do hit it ;-/
next prev parent reply other threads:[~2019-03-07 2:18 UTC|newest]
Thread overview: 53+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-03 10:22 KASAN: use-after-free Read in unix_dgram_poll syzbot
2019-03-03 13:55 ` Al Viro
2019-03-03 15:18 ` [PATCH] aio: prevent the final fput() in the middle of vfs_poll() (Re: KASAN: use-after-free Read in unix_dgram_poll) Al Viro
2019-03-03 18:37 ` Eric Dumazet
2019-03-03 19:44 ` Linus Torvalds
2019-03-03 20:13 ` Linus Torvalds
2019-03-03 20:30 ` Al Viro
2019-03-03 22:23 ` Linus Torvalds
2019-03-04 2:36 ` Al Viro
2019-03-04 21:22 ` Linus Torvalds
2019-03-07 0:03 ` [PATCH 1/8] aio: make sure file is pinned Al Viro
2019-03-07 0:03 ` [PATCH 2/8] aio_poll_wake(): don't set ->woken if we ignore the wakeup Al Viro
2019-03-07 2:18 ` Al Viro [this message]
2019-03-08 11:16 ` zhengbin (A)
2019-03-07 0:03 ` [PATCH 3/8] aio_poll(): sanitize the logics after vfs_poll(), get rid of leak on error Al Viro
2019-03-07 2:11 ` zhengbin (A)
2019-03-07 0:03 ` [PATCH 4/8] aio_poll(): get rid of weird refcounting Al Viro
2019-03-07 0:03 ` [PATCH 5/8] make aio_read()/aio_write() return int Al Viro
2019-03-07 0:03 ` [PATCH 6/8] move dropping ->ki_eventfd into iocb_put() Al Viro
2019-03-07 0:03 ` [PATCH 7/8] deal with get_reqs_available() in aio_get_req() itself Al Viro
2019-03-07 0:03 ` [PATCH 8/8] aio: move sanity checks and request allocation to io_submit_one() Al Viro
2019-03-07 0:23 ` [PATCH 1/8] aio: make sure file is pinned Linus Torvalds
2019-03-07 0:41 ` Al Viro
2019-03-07 0:48 ` Al Viro
2019-03-07 1:20 ` Al Viro
2019-03-07 1:30 ` Linus Torvalds
2019-03-08 3:36 ` Al Viro
2019-03-08 15:50 ` Christoph Hellwig
2019-03-10 7:06 ` Al Viro
2019-03-10 7:08 ` [PATCH 1/8] pin iocb through aio Al Viro
2019-03-10 7:08 ` [PATCH 2/8] keep io_event in aio_kiocb Al Viro
2019-03-11 19:43 ` Christoph Hellwig
2019-03-11 21:17 ` Al Viro
2019-03-10 7:08 ` [PATCH 3/8] aio: store event at final iocb_put() Al Viro
2019-03-11 19:44 ` Christoph Hellwig
2019-03-11 21:13 ` Al Viro
2019-03-11 22:52 ` Al Viro
2019-03-10 7:08 ` [PATCH 4/8] Fix aio_poll() races Al Viro
2019-03-11 19:58 ` Christoph Hellwig
2019-03-11 21:06 ` Al Viro
2019-03-12 19:18 ` Christoph Hellwig
2019-03-10 7:08 ` [PATCH 5/8] make aio_read()/aio_write() return int Al Viro
2019-03-11 19:44 ` Christoph Hellwig
2019-03-10 7:08 ` [PATCH 6/8] move dropping ->ki_eventfd into iocb_destroy() Al Viro
2019-03-11 19:46 ` Christoph Hellwig
2019-03-10 7:08 ` [PATCH 7/8] deal with get_reqs_available() in aio_get_req() itself Al Viro
2019-03-11 19:46 ` Christoph Hellwig
2019-03-10 7:08 ` [PATCH 8/8] aio: move sanity checks and request allocation to io_submit_one() Al Viro
2019-03-11 19:48 ` Christoph Hellwig
2019-03-11 21:12 ` Al Viro
2019-03-11 19:41 ` [PATCH 1/8] pin iocb through aio Christoph Hellwig
2019-03-11 19:41 ` [PATCH 1/8] aio: make sure file is pinned Christoph Hellwig
2019-03-04 7:53 ` [PATCH] aio: prevent the final fput() in the middle of vfs_poll() (Re: KASAN: use-after-free Read in unix_dgram_poll) Dmitry Vyukov
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