Commit e12d7a46 authored by Jens Axboe's avatar Jens Axboe
Browse files

io_uring/msg_ring: fix missing lock on overflow for IOPOLL 

If the target ring is configured with IOPOLL, then we always need to hold
the target ring uring_lock before posting CQEs. We could just grab it
unconditionally, but since we don't expect many target rings to be of this
type, make grabbing the uring_lock conditional on the ring type.

Link: https://lore.kernel.org/io-uring/Y8krlYa52%2F0YGqkg@ip-172-31-85-199.ec2.internal/


Reported-by: default avatarXingyuan Mo <hdthky0@gmail.com>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 423d5081

io_uring/msg_ring.c

+30 −9
Original line number Diff line number Diff line
@@ -65,20 +65,33 @@ static void io_msg_tw_complete(struct callback_head *head) 
	struct io_ring_ctx *target_ctx = req->file->private_data;

	int ret = 0;



	if (current->flags & PF_EXITING)

	if (current->flags & PF_EXITING) {

		ret = -EOWNERDEAD;

	else if (!io_post_aux_cqe(target_ctx, msg->user_data, msg->len, 0))

	} else {

		/*

		 * If the target ring is using IOPOLL mode, then we need to be

		 * holding the uring_lock for posting completions. Other ring

		 * types rely on the regular completion locking, which is

		 * handled while posting.

		 */

		if (target_ctx->flags & IORING_SETUP_IOPOLL)

			mutex_lock(&target_ctx->uring_lock);

		if (!io_post_aux_cqe(target_ctx, msg->user_data, msg->len, 0))

			ret = -EOVERFLOW;

		if (target_ctx->flags & IORING_SETUP_IOPOLL)

			mutex_unlock(&target_ctx->uring_lock);

	}



	if (ret < 0)

		req_set_fail(req);

	io_req_queue_tw_complete(req, ret);

}



static int io_msg_ring_data(struct io_kiocb *req)

static int io_msg_ring_data(struct io_kiocb *req, unsigned int issue_flags)

{

	struct io_ring_ctx *target_ctx = req->file->private_data;

	struct io_msg *msg = io_kiocb_to_cmd(req, struct io_msg);

	int ret;



	if (msg->src_fd || msg->dst_fd || msg->flags)

		return -EINVAL;
@@ -93,10 +106,18 @@ static int io_msg_ring_data(struct io_kiocb *req) 
		return IOU_ISSUE_SKIP_COMPLETE;

	}



	ret = -EOVERFLOW;

	if (target_ctx->flags & IORING_SETUP_IOPOLL) {

		if (unlikely(io_double_lock_ctx(target_ctx, issue_flags)))

			return -EAGAIN;

		if (io_post_aux_cqe(target_ctx, msg->user_data, msg->len, 0))

		return 0;



	return -EOVERFLOW;

			ret = 0;

		io_double_unlock_ctx(target_ctx);

	} else {

		if (io_post_aux_cqe(target_ctx, msg->user_data, msg->len, 0))

			ret = 0;

	}

	return ret;

}



static struct file *io_msg_grab_file(struct io_kiocb *req, unsigned int issue_flags)
@@ -223,7 +244,7 @@ int io_msg_ring(struct io_kiocb *req, unsigned int issue_flags) 


	switch (msg->cmd) {

	case IORING_MSG_DATA:

		ret = io_msg_ring_data(req);

		ret = io_msg_ring_data(req, issue_flags);

		break;

	case IORING_MSG_SEND_FD:

		ret = io_msg_send_fd(req, issue_flags);