Re: [PATCH 1/2] io_uring: fix ->work corruption with poll_add

[Pavel Begunkov <asml.silence@gmail.com>]

On 24/07/2020 20:07, Pavel Begunkov wrote:
> req->work might be already initialised by the time it gets into
> __io_arm_poll_handler(), which will corrupt it be using fields that are
s/be using/by using/

Jens, could you please fold it in, if the patch would do? Or let me know
and I'll resend.

> in an union with req->work. Luckily, the only side effect is missing
> put_creds(). Clean req->work before going there.
> 
> Suggested-by: Jens Axboe <axboe@kernel.dk>
> Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
> ---
>  fs/io_uring.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/fs/io_uring.c b/fs/io_uring.c
> index 32b0064f806e..98e8079e67e7 100644
> --- a/fs/io_uring.c
> +++ b/fs/io_uring.c
> @@ -4658,6 +4658,10 @@ static int io_poll_add(struct io_kiocb *req)
>  	struct io_poll_table ipt;
>  	__poll_t mask;
>  
> +	/* ->work is in union with hash_node and others */
> +	io_req_work_drop_env(req);
> +	req->flags &= ~REQ_F_WORK_INITIALIZED;
> +
>  	INIT_HLIST_NODE(&req->hash_node);
>  	INIT_LIST_HEAD(&req->list);
>  	ipt.pt._qproc = io_poll_queue_proc;
> 

-- 
Pavel Begunkov