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Subject: Re: [PATCH 5.6] io_uring: NULL-deref for IOSQE_{ASYNC,DRAIN}
To:     Pavel Begunkov <asml.silence@gmail.com>, io-uring@vger.kernel.org,
        linux-kernel@vger.kernel.org
References: <3fff749b19ae1c3c2d59e88462a8a5bfc9e6689f.1584127615.git.asml.silence@gmail.com>
From:   Jens Axboe <axboe@kernel.dk>
Message-ID: <62bc8817-5777-7f79-3c27-028a770e2f3b@kernel.dk>
Date:   Sat, 14 Mar 2020 09:58:38 -0600
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On 3/13/20 1:29 PM, Pavel Begunkov wrote:
> Processing links, io_submit_sqe() prepares requests, drops sqes, and
> passes them with sqe=NULL to io_queue_sqe(). There IOSQE_DRAIN and/or
> IOSQE_ASYNC requests will go through the same prep, which doesn't expect
> sqe=NULL and fail with NULL pointer deference.
> 
> Always do full prepare including io_alloc_async_ctx() for linked
> requests, and then it can skip the second preparation.

Thanks, applied.

-- 
Jens Axboe