From: Jens Axboe <axboe@kernel.dk>
To: Pavel Begunkov <asml.silence@gmail.com>,
linux-block@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [BUG] io_uring: defer logic based on shared data
Date: Fri, 25 Oct 2019 10:32:48 -0600 [thread overview]
Message-ID: <df3b9edd-86ad-5460-b61b-66707c0fb630@kernel.dk> (raw)
In-Reply-To: <96446fe1-4f32-642b-7100-ebfa291d7127@kernel.dk>
On 10/25/19 10:27 AM, Jens Axboe wrote:
> On 10/25/19 10:21 AM, Pavel Begunkov wrote:
>> On 25/10/2019 19:03, Jens Axboe wrote:
>>> On 10/25/19 3:55 AM, Pavel Begunkov wrote:
>>>> I found 2 problems with __io_sequence_defer().
>>>>
>>>> 1. it uses @sq_dropped, but doesn't consider @cq_overflow
>>>> 2. @sq_dropped and @cq_overflow are write-shared with userspace, so
>>>> it can be maliciously changed.
>>>>
>>>> see sent liburing test (test/defer *_hung()), which left an unkillable
>>>> process for me
>>>
>>> OK, how about the below. I'll split this in two, as it's really two
>>> separate fixes.
>> cached_sq_dropped is good, but I was concerned about cached_cq_overflow.
>> io_cqring_fill_event() can be called in async, so shouldn't we do some
>> synchronisation then?
>
> We should probably make it an atomic just to be on the safe side, I'll
> update the series.
Here we go, patch 1:
http://git.kernel.dk/cgit/linux-block/commit/?h=for-linus&id=f2a241f596ed9e12b7c8f960e79ccda8053ea294
patch 2:
http://git.kernel.dk/cgit/linux-block/commit/?h=for-linus&id=b7d0297d2df5bfa0d1ecf9d6c66d23676751ef6a
--
Jens Axboe
next prev parent reply other threads:[~2019-10-25 16:32 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-25 9:55 [BUG] io_uring: defer logic based on shared data Pavel Begunkov
2019-10-25 16:03 ` Jens Axboe
2019-10-25 16:09 ` Jens Axboe
2019-10-25 16:21 ` Jens Axboe
2019-10-25 16:21 ` Pavel Begunkov
2019-10-25 16:27 ` Jens Axboe
2019-10-25 16:32 ` Jens Axboe [this message]
2019-10-25 16:40 ` Pavel Begunkov
2019-10-25 16:44 ` Jens Axboe
2019-10-25 16:55 ` Pavel Begunkov
2019-10-25 16:57 ` Jens Axboe
2019-10-25 18:13 ` Pavel Begunkov
2019-10-25 18:17 ` Jens Axboe
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