Re: [PATCH 2/3] io_uring: Use submit info inlined into req

[Jens Axboe <axboe@kernel.dk>]

On 11/5/19 4:04 PM, Pavel Begunkov wrote:
 				if (unlikely(!shadow_req))
> @@ -2716,24 +2712,25 @@ static int io_submit_sqes(struct io_ring_ctx *ctx, unsigned int nr,
>   				shadow_req->flags |= (REQ_F_IO_DRAIN | REQ_F_SHADOW_DRAIN);
>   				refcount_dec(&shadow_req->refs);
>   			}
> -			shadow_req->sequence = s.sequence;
> +			shadow_req->sequence = req->submit.sequence;
>   		}
>   
>   out:
> -		s.ring_file = ring_file;
> -		s.ring_fd = ring_fd;
> -		s.has_user = *mm != NULL;
> -		s.in_async = async;
> -		s.needs_fixed_file = async;
> -		trace_io_uring_submit_sqe(ctx, s.sqe->user_data, true, async);
> -		io_submit_sqe(ctx, req, &s, statep, &link);
> +		req->submit.ring_file = ring_file;
> +		req->submit.ring_fd = ring_fd;
> +		req->submit.has_user = *mm != NULL;
> +		req->submit.in_async = async;
> +		req->submit.needs_fixed_file = async;
> +		trace_io_uring_submit_sqe(ctx, req->submit.sqe->user_data,
> +					  true, async);
> +		io_submit_sqe(ctx, req, &req->submit, statep, &link);
>   		submitted++;
>   
>   		/*
>   		 * If previous wasn't linked and we have a linked command,
>   		 * that's the end of the chain. Submit the previous link.
>   		 */
> -		if (!(s.sqe->flags & IOSQE_IO_LINK) && link) {
> +		if (!(req->submit.sqe->flags & IOSQE_IO_LINK) && link) {
>   			io_queue_link_head(ctx, link, &link->submit, shadow_req);
>   			link = NULL;
>   			shadow_req = NULL;

Another potential use-after-free here, as 'req' might have completed by
the time you go and check for IOSQE_IO_LINK.

-- 
Jens Axboe